Radio frequency (RF) polarization rotation devices and systems for interference mitigation

ABSTRACT

Aspects of the subject disclosure may include, for example, receiving, by a radio frequency (RF) mechanical device, signals relating to one or more crossed-dipole radiating elements of an antenna system, performing, by the RF mechanical device, polarization rotation of the signals to derive output signals having polarizations that are rotated in a manner that mimics physical rotation of the one or more crossed-dipole radiating elements, and providing, by the RF mechanical device, the output signals to enable avoidance of interference. Other embodiments are disclosed.

FIELD OF THE DISCLOSURE

The subject disclosure relates to polarization rotation devices andsystems for interference/passive intermodulation (PIM) mitigation oravoidance.

BACKGROUND

In most environments involving short range or long range wirelesscommunications, interference from unexpected sources can negativelyimpact system performance. For instance, interference can result inlower throughput, dropped calls, and reduced bandwidth, and undesirablylead to traffic congestion or other adverse effects. Some wirelessservice providers have addressed interference issues by adding morecommunication nodes, policing interferers, or utilizing antenna steeringtechniques to avoid interferers.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will now be made to the accompanying drawings, which are notnecessarily drawn to scale, and wherein:

FIG. 1A is a block diagram illustrating an exemplary, non-limitingembodiment of a communications network in accordance with variousaspects described herein.

FIG. 1B depicts an exemplary, non-limiting embodiment of acommunications system functioning within, or operatively overlaid upon,the communications network of FIG. 1A in accordance with various aspectsdescribed herein.

FIG. 2A is a block diagram illustrating an example, non-limitingembodiment of a system functioning within, or operatively overlaid upon,the communications network of FIG. 1A and/or the communications systemof FIG. 1B in accordance with various aspects described herein.

FIGS. 2B-2D are diagrams illustrating example, non-limiting embodimentsof polarization adjusting and associated equations in accordance withvarious aspects described herein.

FIG. 2E illustrates a conceptualization of flexible polarizationadjusting for transmit (Tx) and receive (Rx) across various frequencybands of an example multi-band antenna in accordance with variousaspects described herein.

FIG. 3A is a block diagram illustrating an example, non-limitingembodiment of a communications system that includes an antenna and aradio frequency (RF) polarization shifting module/system (or RF PIMmitigator) (RPM) for interference/PIM detection andmitigation/avoidance, and that functions within, or is operativelyoverlaid upon, the communications network of FIG. 1A and/or thecommunications system of FIG. 1B in accordance with various aspectsdescribed herein.

FIGS. 3B and 3C are block diagrams illustrating alternate examplenon-limiting embodiments of a communications system, functioning within,or operatively overlaid upon, the communications network of FIG. 1Aand/or the communications system of FIG. 1B in accordance with variousaspects described herein.

FIGS. 4A-4F are block diagrams illustrating example polarizationshifters in accordance with various aspects described herein.

FIGS. 5A-5D show views of various portions of an example, non-limitingembodiment of a polarization shifter of an RPM in accordance withvarious aspects described herein.

FIG. 6 shows various views of an example, non-limiting embodiment of apolarization shifter of an RPM in accordance with various aspectsdescribed herein.

FIG. 7A is a block diagram of an example, non-limiting embodiment of apolarization shifter of an RPM in operation with a motor and a driveassembly in accordance with various aspects described herein.

FIG. 7B is a perspective view of an example, non-limiting embodiment ofa motor and a drive assembly adapted to provide linear forces to apolarization shifter in accordance with various aspects describedherein.

FIG. 7C is a perspective view of an example, non-limiting embodiment ofthe motor and the drive assembly of FIG. 7B adapted to providerotational forces to a polarization shifter in accordance with variousaspects described herein.

FIG. 8A is a block diagram of an exemplary, non-limiting embodiment of afunctional architecture of a control unit of an RPM in accordance withvarious aspects described herein.

FIG. 8B illustrates a radiating element and an incoming signal inaccordance with various aspects described herein.

FIG. 8C is a block diagram of an exemplary, non-limiting implementationof a monitoring/detection unit of an RPM in accordance with variousaspects described herein.

FIGS. 8D and 8E illustrate identification of PIM polarization inaccordance with various aspects described herein.

FIG. 9A shows an example orthogonal signal voltage reading table inaccordance with various aspects described herein.

FIG. 9B shows an example component/substrate position table inaccordance with various aspects described herein.

FIGS. 10A and 10B illustrate an example implementation for evaluatingpolarization shifting in accordance with various aspects describedherein.

FIGS. 10C and 10D show mitigation results for different sources of PIMin accordance with various aspects described herein.

FIG. 11A shows graphical representations of a multi-band (i.e.,dual-band) communications system subject to PIM in accordance withvarious aspects described herein.

FIG. 11B is a block diagram illustrating an example, non-limitingembodiment of path/port mapping functionality in a downlink signal pathof a multi-band communications system in accordance with various aspectsdescribed herein.

FIG. 11C is a block diagram illustrating an example, non-limitingembodiment of path/port mapping functionality in downlink signal pathsof single-band communications systems in accordance with various aspectsdescribed herein.

FIG. 11D illustrates an example, non-limiting embodiment of a particularpath/port mapping in a downlink signal path of a multi-bandcommunications system in accordance with various aspects describedherein.

FIG. 11E illustrates a dual-band antenna with default path/port mappingin comparison with altered path/port mapping in accordance with variousaspects described herein.

FIG. 11F is a block diagram illustrating an example, non-limitingembodiment of path/port mapping functionality employed in conjunctionwith polarization rotation functions in a downlink signal path of amulti-band communications system in accordance with various aspectsdescribed herein.

FIG. 11G illustrates a dual-band antenna with altered path/port mappingemployed with polarization rotation in accordance with various aspectsdescribed herein.

FIG. 12A depicts an illustrative embodiment of a method in accordancewith various aspects described herein.

FIG. 12B depicts an illustrative embodiment of a method in accordancewith various aspects described herein.

FIG. 12C depicts an illustrative embodiment of a method in accordancewith various aspects described herein.

FIG. 12D depicts an illustrative embodiment of a method in accordancewith various aspects described herein.

FIG. 13 is a block diagram of an example, non-limiting embodiment of acomputing environment in accordance with various aspects describedherein.

DETAILED DESCRIPTION

In a communications system, a main objective is to increase the signalto interference plus noise ratio (SINR) of a communication channel.Let's take a 2×2 multiple-input-multiple-output (MIMO) case as anexample. MIMO gains over single-input-single-output (SISO) is achievedwhen the SINR of the channel is higher than is necessary to support themaximum SISO data rate. Such high SINR conditions occur when the user isnear the cell center, or when interference from adjacent cells is low.When practical field deployments are taken into account, in a typicalurban macro environment, it is estimated that 2×2 MIMO only providesapproximately 20% gain over SISO. The 2×2 MIMO configuration can beincreased by adding more antennas at each end of the link. In theoriginal 3^(rd) Generation Partnership Project (3GPP) Release 8Long-Term Evolution (LTE) standard in 2008, 2× and 4× operation wasspecified, and 8×8 was added later in Release 10. As the number ofantennas increases, it becomes less likely that the channel will supportorthogonal transmission paths. These orthogonal paths are known asEigenmodes.

The subject disclosure describes, among other things, illustrativeembodiments of polarization shifting (or adjusting) of signals forinterference/PIM mitigation or avoidance. Polarization shifting (oradjusting) of a signal may be effected via a (e.g., mathematical)rotation of the signal. In exemplary embodiments, polarization shifting(or adjusting) may include polarization rotation of orthogonal signalswithout affecting their orthogonality. In the context of acommunications system that includes an antenna with crossed-dipoleradiating elements, polarization shifting of each signal in a pair oforthogonal signals corresponding to a given radiating element mayinvolve defining polarizations/projections that provide a “mixing”effect, where the signals are projected in a different set of axes(e.g., represented by equations 202 p/202 q/202 r described in moredetail below with respect to FIGS. 2B-2D). For instance, crossed-dipoleradiating elements may be oriented in a default (e.g., +45/−45 degree)polarization configuration, and signals associated with these radiatingelements may be orthogonal and oriented in that default polarization(e.g., +45/−45 degrees). Polarization shifting may involve adjusting theorientations of orthogonal signals corresponding to the radiatingelements—e.g., from a +45/−45 degree default orientation to a differentorientation, such as a +30/−60 degree orientation—to effect “rotation”of the two signals. This mimics actual, physical rotation of thoseradiating elements without requiring or involving any movement of theradiating elements or the antenna system housing. Consequently, oneresulting polarization direction (or signal in that polarization) mayreceive/include the interference/PIM and the other polarizationdirection (or signal in the other polarization) may receive/includelittle to none of the interference/PIM, thereby enabling mitigation oravoidance of the interference/PIM via selective signal extraction/usage.

Exemplary embodiments provide for a radio frequency (RF) polarizationshifting module/system (or RF PIM mitigator) (RPM) that is capable ofperforming the polarization shifting (or adjusting) of signals in the RF(or analog) domain.

In one or more embodiments, the RPM may be implemented as an RFmechanical device that is configured to manipulate orthogonal RFsignals. In various embodiments, the RF mechanical device may includeinput ports for receiving orthogonal RF signals, and output ports thatprovide polarization-adjusted RF signals. In certain embodiments, theports of the RF mechanical device may be reciprocal or symmetrical inthat each port may simultaneously function as an input port and anoutput port. In these embodiments, where a given dipole elementcorresponding to an RF line (and port of a communications system)operates in both the transmit (Tx) and receive (Rx) directions and/oroperates in multiple frequency bands, signal manipulation by the RFmechanical device may (e.g., equally) affect both the Tx and Rx signalson that RF line across the multiple bands.

In exemplary embodiments, the RF mechanical device may include hybridcoupler(s) and mechanically-adjustable dual simultaneous phase-shiftingcoupler(s). In one or more embodiments, a mechanically-adjustable dualsimultaneous phase-shifting coupler may be implemented as a dualtrombone shifter that is linearly adjustable. In alternativeembodiments, a mechanically-adjustable dual simultaneous phase-shiftingcoupler may be implemented as a dual (overlapping) arch shifter that isrotatably adjustable.

Referring to the dual trombone shifter implementation as an example, thedevice may include two 90 degree hybrid couplers for coupling to inputand output (feed) networks. Each hybrid coupler may be coupled to arespective transmission line disposed on a bottom substrate, where thetwo transmission lines have curved portions and are separated from oneanother by a predefined distance. The device may also include a topsubstrate positioned adjacent to (e.g., over) the bottom substrate andhaving disposed thereon two curved transmission lines that at leastpartially overlap with the transmission lines on the bottom substrateand that, along with portions of the bottom transmission lines, form thedual trombone shifter. A dielectric layer may reside between the bottomsubstrate and the top substrate for transmission line coupling. Byvirtue of the arrangement of the hybrid couplers and the dual tromboneshifter, the overlapping coupling between the transmission lines on thetop substrate and the transmission lines on the bottom substrate, andthe curved shapes and dimensions of the top and bottom transmissionlines, mechanical adjustments to the dual trombone shifter—e.g., viacontrolled linear movement of the top substrate relative to the bottomsubstrate (resembling the sliding in/out of two trombones; hence, thedescriptive “dual trombone”)—may provide dual, simultaneous phaseshifting effects that result in the above-described “rotation” of therespective polarizations of orthogonal RF input signals, withoutaffecting orthogonality of the signals.

Embodiments of the RPM may be implemented in any portion of an RF chainof a communications system. For instance, in various embodiments, someor all of the aspects of the RPM may be implemented/integrated in a(e.g., standalone) construction or device that interfaces an antennasystem and a radio (e.g., a remote radio head (RRH) or a remote radiounit (RRU)) of the communications system, and may provide forinterference/PIM mitigation or avoidance independently of the radioand/or based on commands from the radio.

In one or more embodiments, some or all of the aspects of the RPM mayadditionally, or alternatively, be integrated in the antenna system(i.e., within a housing of the antenna system (e.g., as part of smartantenna functionality)) independently of the radio and/or based oncommands from the radio.

In one or more embodiments, some or all of the aspects of the RPM mayadditionally, or alternatively, be implemented/integrated in the radio,where polarization adjusting may be performed for Tx only, for Rx only,or for both Tx and Rx. Polarization adjustments for Tx and Rx may be thesame, similar, or different. Polarization adjusting may also beperformed in the same manner, in a similar manner, or differently for Txand Rx. In some of these embodiments, where the radio provides access toindividual Tx and Rx signals across the different RF lines and/or acrossthe different frequency bands (thus obviating the need to considerconstraints relating to reciprocality and nonlinearities associated withhigh power RF), the design of the RPM may be simplified. For instance,while in certain embodiments, the RPM may be implemented in a radiousing the above-described RF mechanical device (e.g., with hybridcoupler(s) and mechanically-adjustable dual simultaneous phase-shiftingcoupler(s)), in other embodiments, the RPM may additionally oralternatively be implemented using other RF devices and/or RF-basedtechniques to manipulate signals in an RF path.

It is to be understood and appreciated that, regardless of where the RPMis implemented (whether in the radio, the antenna, or as a standalonedevice), some or all of the aspects of the RPM may nevertheless include,or be implemented in, one or more RF devices, such as RF circuits and/orcomponents configured to alter/combine (in the RF domain) phase(s)and/or amplitudes of signals to be transmitted and/or signals that arereceived.

Exemplary embodiments described herein also provide for polarizationshifting (or adjusting) of signals that is effected electronicallyand/or in the digital domain. Electronic and/or digital manipulation ofsignals involves both real and complex (I/Q) values, and thus enablesprocessing techniques that are difficult to implement using real numbersalone (i.e., in the RF domain). In any case, electronic and/or digitalprocessing or manipulation (e.g., based on the equations 202 p/202 q/202r described in more detail below with respect to FIGS. 2B-2D orequivalents of equations 202 p/202 q/202 r) can similarly effect theabove-described (e.g., mathematical) rotation of signals to mimicactual, physical rotation of radiating elements without requiring orinvolving any movement of the radiating elements or the antenna systemhousing.

In various embodiments, electronic and/or digital manipulation ofsignals may be implemented in a radio. With access to individual Tx andRx signals across different RF lines and/or across different frequencybands, electronic- or digital-based polarization shifting of signals canbe flexibly implemented without the need to consider constraintsrelating to reciprocality and nonlinearities associated with high powerRF.

A Common Public Radio Interface (CPRI) device (e.g., server) may bedeployed on a CPRI uplink (UL) between a radio and a baseband unit (BBU)of a communications system, and may be configured to analyze andmanipulate baseband I/Q data to remove various types and sources ofinterference and provide insight into overall spectrum health. Forinstance, a CPRI device may be capable of performing PIM cancellation,SINR optimization, narrow/wideband interference cancellation, etc. Inone or more embodiments, electronic and/or digital manipulation ofsignals may additionally, or alternatively, be implemented in a CPRIdevice. While a CPRI device might not have flexible access to individualTx and Rx signals across different RF lines and/or across differentfrequency bands, electronic and/or digital manipulation of signals(e.g., based on the equations 202 p/202 q/202 r described in more detailbelow with respect to FIGS. 2B-2D or equivalents of equations 202 p/202q/202 r) may nevertheless be performed based on I/Q data to effectsignal rotations.

Based on an analysis of known or likely interference/PIM levels,characteristics, and/or combinations, proper selection of polarizationshifting/adjusting parameters/values, phase shifts, and/or the like maybe determined and utilized to facilitate interference/PIM mitigation oravoidance. For instance, adjusting the polarization of orthogonal RFsignals such that one resulting polarization direction (or signal inthat polarization) receives/includes the interference/PIM and the otherpolarization direction (or signal in the other polarization)receives/includes little to none of the interference/PIM enablesmitigation or avoidance of the interference/PIM via selective signalextraction/usage. Additionally, or alternatively, downlink (DL) signalscan be manipulated or otherwise influenced in a way that minimizes orreduces the amount of interference/PIM that is received in the UL, whichcan improve overall UL performance and coverage. The principle oforthogonality between the different modes of transmission can also betaken into account, where interference/PIM source(s) minimally interactwith transmissions, thereby reducing the level of interference/PIMdetected/received by a communications system.

In various embodiments, some or all of the polarization shiftingfunctionality provided by any of the RPM implementation(s) or viaelectronic and/or digital processing may be performed automatically(based on detected interference/PIM levels) by one or more smartdetection/mitigation/cancellation devices, systems, and/or algorithms.In certain embodiments, some or all of the polarization shiftingfunctionality may be performed manually—e.g., by one or more operatorsor administrators in light of detected interference/PIM level(s). Inthese embodiments, one or more preset conditions or settings (e.g.,relating to particular adjustments, such as physical (e.g., linearand/or rotational) displacement values, polarization/projection amountsor values, etc.) may be available for user selection, and may, whenselected, cause the appropriate polarization shifting to be effectedaccordingly.

It is to be understood and appreciated that implementations of the RPMmay perform interference/PIM mitigation similar to that provided byphysical rotation of radiating elements and/or CPRI-based PIMmitigation, but is distinguished therefrom since the RPM interceptssignals in the RF domain.

In certain embodiments, some or all of the aspects of the polarizationshifting functionality provided by any of the RPM implementation(s) orvia electronic and/or digital processing may be combined with each otherand/or with one or more other interference/PIM mitigation or avoidancetechniques. For instance, either or both of RPM-based polarizationadjusting and electronic-/digital-based polarization adjusting may becombined with physical rotation of radiating elements and/orhardware-based (and/or software-based) signal conditioning of (e.g., UL)signals to provide overall (e.g., complementary) interference/PIMmitigation or avoidance.

In some embodiments, various polarization shifting techniques describedherein can be exploited in time-division duplex (TDD) systems and/orfrequency-division duplex (FDD) systems to relax, loosen, or otherwisedecrease the number of system implementation requirements, such as thoserelating to guard times/bands in TDD and frequency separation in FDD.

One or more aspects of the subject disclosure include a polarizationrotation system. The polarization rotation system may include a radiofrequency (RF) mechanical device. The polarization rotation system mayfurther include a plurality of reciprocal ports for the RF mechanicaldevice, the plurality of reciprocal ports including a first pair ofreciprocal ports as inputs for the RF mechanical device, and a secondpair of reciprocal ports as outputs for the RF mechanical device, the RFmechanical device being configured to perform polarization rotation ofsignals to enable avoidance of interference.

One or more aspects of the subject disclosure include a method. Themethod may include receiving, by a radio frequency (RF) mechanicaldevice, signals relating to one or more crossed-dipole radiatingelements of an antenna system, performing, by the RF mechanical device,polarization rotation of the signals to derive output signals havingpolarizations that are rotated in a manner that mimics physical rotationof the one or more crossed-dipole radiating elements, and providing, bythe RF mechanical device, the output signals to enable avoidance ofinterference.

One or more aspects of the subject disclosure include a communicationssystem. The communications system may include an antenna having multiplearrays of orthogonally-polarized radiating elements, and a devicearranged to communicatively couple with one or more arrays of themultiple arrays of orthogonally-polarized radiating elements, the devicebeing configured to perform polarization rotation of signals relating tothe one or more arrays, the polarization rotation mimicking physicalrotation of the one or more arrays and enabling mitigation ofinterference.

Other embodiments are described in the subject disclosure.

Referring now to FIG. 1A, a block diagram is shown illustrating anexample, non-limiting embodiment of a system 100 in accordance withvarious aspects described herein. For example, system 100 canfacilitate, in whole or in part, providing or effecting of polarizationshifting to mitigate or avoid detected interference/PIM. In particular,a communications network 125 is presented for providing broadband access110 to a plurality of data terminals 114 via access terminal 112,wireless access 120 to a plurality of mobile devices 124 and vehicle 126via base station or access point 122, voice access 130 to a plurality oftelephony devices 134, via switching device 132 and/or media access 140to a plurality of audio/video display devices 144 via media terminal142. In addition, communications network 125 is coupled to one or morecontent sources 175 of audio, video, graphics, text and/or other media.While broadband access 110, wireless access 120, voice access 130 andmedia access 140 are shown separately, one or more of these forms ofaccess can be combined to provide multiple access services to a singleclient device (e.g., mobile devices 124 can receive media content viamedia terminal 142, data terminal 114 can be provided voice access viaswitching device 132, and so on).

The communications network 125 includes a plurality of network elements(NE) 150, 152, 154, 156, etc. for facilitating the broadband access 110,wireless access 120, voice access 130, media access 140 and/or thedistribution of content from content sources 175. The communicationsnetwork 125 can include a circuit switched or packet switched network, avoice over Internet protocol (VoIP) network, Internet protocol (IP)network, a cable network, a passive or active optical network, a 4G, 5G,or higher generation wireless access network, WIMAX network,Ultra-wideband network, personal area network or other wireless accessnetwork, a broadcast satellite network and/or other communicationsnetwork.

In various embodiments, the access terminal 112 can include a digitalsubscriber line access multiplexer (DSLAM), cable modem terminationsystem (CMTS), optical line terminal (OLT) and/or other access terminal.The data terminals 114 can include personal computers, laptop computers,netbook computers, tablets or other computing devices along with digitalsubscriber line (DSL) modems, data over coax service interfacespecification (DOCSIS) modems or other cable modems, a wireless modemsuch as a 4G, 5G, or higher generation modem, an optical modem and/orother access devices.

In various embodiments, the base station or access point 122 can includea 4G, 5G, or higher generation base station, an access point thatoperates via an 802.11 standard such as 802.11n, 802.11ac or otherwireless access terminal. The mobile devices 124 can include mobilephones, e-readers, tablets, phablets, wireless modems, and/or othermobile computing devices.

In various embodiments, the switching device 132 can include a privatebranch exchange or central office switch, a media services gateway, VoIPgateway or other gateway device and/or other switching device. Thetelephony devices 134 can include traditional telephones (with orwithout a terminal adapter), VoIP telephones and/or other telephonydevices.

In various embodiments, the media terminal 142 can include a cablehead-end or other TV head-end, a satellite receiver, gateway or othermedia terminal 142. The display devices 144 can include televisions withor without a set top box, personal computers and/or other displaydevices.

In various embodiments, the content sources 175 include broadcasttelevision and radio sources, video on demand platforms and streamingvideo and audio services platforms, one or more content data networks,data servers, web servers and other content servers, and/or othersources of media.

In various embodiments, the communications network 125 can includewired, optical and/or wireless links and the network elements 150, 152,154, 156, etc. can include service switching points, signal transferpoints, service control points, network gateways, media distributionhubs, servers, firewalls, routers, edge devices, switches and othernetwork nodes for routing and controlling communications traffic overwired, optical and wireless links as part of the Internet and otherpublic networks as well as one or more private networks, for managingsubscriber access, for billing and network management and for supportingother network functions.

FIG. 1B depicts an exemplary, non-limiting embodiment of atelecommunication system 180 functioning within, or operatively overlaidupon, the communications network 100 of FIG. 1A in accordance withvarious aspects described herein. For example, system 180 canfacilitate, in whole or in part, providing or effecting of polarizationshifting to mitigate or avoid detected interference/PIM. As shown inFIG. 1B, the telecommunication system 180 may include mobile units 182,183A, 183B, 183C, and 183D, a number of base stations, two of which areshown in FIG. 1B at reference numerals 184 and 186, and a switchingstation 188 to which each of the base stations 184, 186 may beinterfaced. The base stations 184, 186 and the switching station 188 maybe collectively referred to as network infrastructure.

During operation, the mobile units 182, 183A, 183B, 183C, and 183Dexchange voice, data or other information with one of the base stations184, 186, each of which is connected to a conventional land linecommunications network. For instance, information, such as voiceinformation, transferred from the mobile unit 182 to one of the basestations 184, 186 is coupled from the base station to the communicationsnetwork to thereby connect the mobile unit 182 with, for example, a landline telephone so that the land line telephone may receive the voiceinformation. Conversely, information, such as voice information may betransferred from a land line communications network to one of the basestations 184, 186, which in turn transfers the information to the mobileunit 182.

The mobile units 182, 183A, 183B, 183C, and 183D and the base stations184, 186 may exchange information in either narrow band or wide bandformat. For the purposes of this description, it is assumed that themobile unit 182 is a narrowband unit and that the mobile units 183A,183B, 183C, and 183D are wideband units. Additionally, it is assumedthat the base station 184 is a narrowband base station that communicateswith the mobile unit 182 and that the base station 186 is a widebanddigital base station that communicates with the mobile units 183A, 183B,183C, and 183D.

Narrow band format communication takes place using, for example,narrowband 200 kilohertz (KHz) channels. The Global system for mobilephone systems (GSM) is one example of a narrow band communication systemin which the mobile unit 182 communicates with the base station 184using narrowband channels. Alternatively, the mobile units 183A, 183B,183C, and 183D communicate with the base station 186 using a form ofdigital communications such as, for example, code-division multipleaccess (CDMA), Universal Mobile Telecommunications System (UMTS), 3GPPLong Term Evolution (LTE), or other next generation wireless accesstechnologies. CDMA digital communication, for instance, takes placeusing spread spectrum techniques that broadcast signals having widebandwidths, such as, for example, 1.2288 megahertz (MHz) bandwidths. Theterms narrowband and wideband referred to above can be replaced withsub-bands, concatenated bands, bands between carrier frequencies(carrier aggregation), and so on, without departing from the scope ofthe subject disclosure.

The switching station 188 is generally responsible for coordinating theactivities of the base stations 184, 186 to ensure that the mobile units182, 183A, 183B, 183C, and 183D are constantly in communication with thebase station 184, 186 or with some other base stations that aregeographically dispersed. For example, the switching station 188 maycoordinate communication handoffs of the mobile unit 182 between thebase station 184 and another base station as the mobile unit 182 roamsbetween geographic areas that are covered by the two base stations.

In various circumstances, the telecommunication system 180, and moreparticularly, one or more of the base stations 184, 186 can beundesirably subjected to interference. Interference can representemissions within band (narrowband or wideband), out-of-band interferers,interference sources outside cellular (e.g., TV stations, commercialradio or public safety radio), interference signals from other carriers(inter-carrier interference), interference signals from UEs operating inadjacent base stations, PIM, and so on. Interference can represent anyforeign signal that can affect communications between communicationdevices (e.g., a UE served by a particular base station).

FIG. 2A is a block diagram illustrating an example, non-limitingembodiment of a system 200 functioning within, or operatively overlaidupon, the communications network 100 of FIG. 1A and/or thecommunications system 180 of FIG. 1B in accordance with various aspectsdescribed herein. As depicted, the system 200 can include an antenna (orantenna system) 210 and an RPM 220. In various embodiments, the antenna210 may include multiple radiating elements. In one or more embodiments,the antenna 210 may include multiple columns and/or rows of radiatingelements, forming one or more antenna arrays or panels. As shown in FIG.2A, the antenna 210 can be associated with various spatial regions,including a reactive near-field region 200 c, a radiating near-fieldregion 200 d, a far-field region 200 f, and an intermediate region 200i. One or more UEs/users 200 u may be located in the far-field region200 f. The intermediate region 200 i may include a zone that overlaps aportion of the radiating near-field region 200 d and a portion of thefar-field region 200 f.

As depicted in FIG. 2A, the antenna 210 and/or the RPM 220 may bedisposed or deployed on a structure, such as a building rooftop. It isto be appreciated and understood that the antenna 210 and the RPM 220may be deployed in any suitable manner. As one example, the antenna 210and/or the RPM 220 may be mounted on one or more towers where few or noobjects may be located nearby (e.g., an unobstructed antenna on atower), and thus a far-field representation may be adequate. As anotherexample, multiple antennas 210 and/or multiple RPMs 220 may be locatedwithin close proximity to one another (e.g., within a threshold distancefrom one another), where the antennas 210 may or may not haveoverlapping degrees of coverage, and thus the near-field region may havean impact on antenna performance. As yet another example, one or moreantennas 210 and/or one or more RPMs 220 may be deployed on buildingrooftop(s) in densely-populated areas (e.g., towns or cities).

In various antenna deployments, antennas (or more particularly, the UL)may be subject to interference and/or PIM—e.g., a PIM source 200 p. PIMinterference may be due to nonlinearities external to antennas that,when subjected to electromagnetic waves emitted by antenna elements inthe DL frequency band, generate reflections at frequencies in the ULfrequency band. PIM interference may also be due to antenna(s) of a basestation transmitting and receiving in DL and UL frequency bands that areclose to one another, or due to different antennas of different basestations transmitting in frequency bands that are close to one another.In these cases, intermodulation of signals transmitted in different (butsufficiently close) frequencies can result in passive signals fallinginto an UL frequency band. In any case, interference/PIM decreases ULsensitivity and thus negatively impacts UL coverage, reliability,performance, and data speeds.

In exemplary embodiments, the RPM 220 may be capable of effectingpolarization shifting (or adjusting) of orthogonal signals in the RFdomain. In various embodiments, the RPM 220 may be implemented as (ormay include) one or more RF mechanical devices. In these embodiments,the RPM 220 may include a respective RF mechanical device for each setor column of radiating elements of the antenna 210 (or for two or moresets or columns of radiating elements of the antenna 210). In certainembodiments, the RF mechanical device may include hybrid coupler(s) andmechanically-adjustable dual simultaneous phase-shifting coupler(s)(e.g., as described in more detail below with respect to one or more ofFIGS. 5A-5C and 6).

FIGS. 2B-2D are diagrams illustrating example, non-limiting embodimentsof polarization adjusting and associated equations in accordance withvarious aspects described herein. As shown in FIG. 2B, the polarizationsof signals transmitted/received by an orthogonally-polarized pair ofelements, such as a crossed-dipole antenna 202 u, 202 v, may be changed.Here, suppose signals s₁(t) and s₂(t) are transmitted/received by the+45 degree dipole 202 u and the −45 degree dipole 202 v,respectively—that is, where signal s₁(t) may be transmitted/receivedwith a +45 degree polarization and signal s₂(t) may betransmitted/received with a −45 degree polarization. In a case where(e.g., based on a desire to mitigate or cancel interference/PIM, such aslikely PIM combinations) there is a need to “rotate” or modify thepolarization of the signal s₁(t) to 90 degrees (e.g., horizontal) andthe polarization of the signal s₂(t) to 0 degrees (e.g., vertical),equations 202 p can be applied to derive new signals s₁′(t) and s₂′(t).As shown, the new signals can be computed or derived byprocessing/manipulating (or mixing) the original signals s₁(t) ands₂(t), which is equivalent to a “rotation” of the crossed-dipole antennaby an angle 202 w (here, for example, 45 degrees in thecounter-clockwise direction). In this way, when signals s₁′(t) ands₂′(t) are transmitted/received from the +45 dipole and the −45 dipole,it is equivalent to transmitting/receiving s₁(t) and s₂(t) from dipolesoriented at 90 degrees and 0 degrees. Selection of certain polarizationscan be viewed as a projection of signals in different axes. The weightsin the polarization shifting equations 202 p are real values (ratherthan complex values), and operate to mathematically adjust theorthogonal signals to desired polarizations. In exemplary embodiments,the RPM 220 may be configured to perform polarization adjusting oforthogonal signals (in the RF domain) in accordance with the equations202 p.

In various embodiments, the RPM 220 may be configured to performpolarization shifting of orthogonal signals (in the RF domain) for Txonly, for Rx only, or for both Tx and Rx. FIG. 2C shows exampleequations 202 q (similar to equations 202 p) that the RPM 220 mayimplement to effect shifting in Tx/Rx directions. The polarizationadjusting (via angle θ_(Tx)) of orthogonal signals on the Tx side(s_(1Tx) and s_(2Tx)) may be the same as or different from thepolarization adjusting (via angle θ_(Rx)) of orthogonal signals on theRx side (s_(1Rx) and s_(2Rx)). Implementation of the RPM 220 in a radio,where there might be access to individual Tx and Rx signals across thedifferent RF lines, can enable more flexible polarization adjusting forTx and Rx (i.e., where angles θ_(Tx) and θ_(Rx) may be different).

In antenna implementations where each radiating element operates inmultiple frequency bands (e.g., a multi-band radio system), the RPM 220may be configured to perform polarization shifting of orthogonal signals(in the RF domain) for one or more of the bands and for Tx only, for Rxonly, or for both Tx and Rx. FIG. 2D shows example equations 202 r thatthe RPM 220 may implement to effect polarization shifting in amulti-band communications system, where “j” represents the differentbands (e.g., Band 1, Band 2, etc.) of the system. Implementation of theRPM 220 in a radio, where there might be access to individual Tx and Rxsignals across the different RF lines and across the different bands,can enable more flexible polarization adjusting for Tx and Rx across thedifferent frequency bands (i.e., where an angle θ_(Tx) for one band maybe the same as or different from an angle θ_(Tx) for another band and/orwhere an angle θ_(Rx) for one band may be the same as or different froman angle θ_(Rx) for another band). FIG. 2E illustrates aconceptualization of flexible polarization adjusting for Tx and Rxacross various frequency bands of an example multi-band antenna inaccordance with various aspects described herein. As shown in FIG. 2E,the multi-band antenna may include crossed-dipole radiatingelements—here, a single column of four crossed-dipole radiating elementsis shown, although the column may include more or fewer crossed-dipoleradiating elements and/or there may be additional columns ofcrossed-dipole radiating elements in the antenna. The crossed-dipoleradiating elements in this example may each be designed to operate in Txand Rx across multiple adjacent frequency bands 1, 2, 3, . . . , j, andcan be treated as a stack or layer of virtual antennas as shown—i.e., asa set of crossed-dipole radiating elements for Rx in Band 1 (Rx₁), a setof crossed-dipole radiating elements for Tx in Band 1 (Tx₁), a set ofcrossed-dipole radiating elements for Rx in Band 2 (Rx₂), a set ofcrossed-dipole radiating elements for Tx in Band 2 (Tx₂), and so on. Thevirtual antennas may be mathematically or virtually rotated (e.g., inaccordance with equations 202 r of FIG. 2D) independently, where theirvirtual rotations are mutually distinct from one another. In this way,the virtual rotation angle or polarization rotation angles (θ_(i),θ_(ii), θ_(iii), θ_(iv), θ_(v), θ_(vi), . . . θ_(m), θ_(n)) may be thesame as or different from one another as needed to avoid interference inthe Rx and Tx directions and across the multiple frequency bands. Forexample, θ_(i) may be the same as or different from θ_(ii), which may bethe same as or different from θ_(iii), and so on. It is to beappreciated and understood that, while the various virtual rotationangles are shown in the clockwise direction, some or all of them mayalternatively be in the counterclockwise direction.

FIG. 3A is a block diagram illustrating an example, non-limitingembodiment of a communications system that includes an antenna 310 andan RPM 320 for interference/PIM detection and mitigation/avoidance inaccordance with various aspects described herein. In variousembodiments, the antenna 310 may be the same as, may be similar to, ormay otherwise correspond to the antenna 210 of FIG. 2A, and the RPM 320may be the same as, may be similar to, or may otherwise correspond tothe RPM 220 of FIG. 2A.

As depicted in FIG. 3A, the antenna 310 may be configured with multiplecolumns 313 u, 313 v, etc. of radiating elements 313 and multiple ports314 h, 314 i, 315 h, 315 i, etc. The antenna 310 and/or the radiatingelements 313 therein (e.g., enclosed within an antenna housing) may haveany shape or combination of shapes with any suitable dimensions,polarizations, etc. In various embodiments, each of the radiatingelements 313 may be designed and positioned such that their radiationpattern(s) exhibit directional, sectoral coverage.

In exemplary embodiments, each radiating element 313 may include anorthogonally-polarized pair of elements. For instance, as depicted, eachradiating element 313 in column 313 u may include orthogonally-polarizedelements 314 a (e.g., oriented for +45 degree polarization) and 314 b(e.g., oriented for −45 degree polarization), and each radiating element313 in column 313 v may include orthogonally-polarized elements 315 a(e.g., oriented for +45 degree polarization) and 315 b (e.g., orientedfor −45 degree polarization).

As depicted in FIG. 3A, the RPM 320 may be communicatively coupled(e.g., via analog/RF line(s)) to the outputs/ports 314 h, 314 i, 315 h,315 i, etc. The radiating elements 313 may be dual port, and althoughnot shown in FIG. 3A, the arrays 313 u, 313 v, etc. may be coupled tothe outputs/ports 314 h, 314 i, 315 h, 315 i, etc. via one or more RFfeed networks. In one or more embodiments, sub-arrays may beindependently fed to the respective antenna ports—e.g., one port foreach sub-array. For instance, the orthogonally-polarized elements 314 aof the radiating elements 313 in column 313 u may (e.g., each) becommunicatively coupled with the port 314 h, the orthogonally-polarizedelements 314 b of the radiating elements 313 in column 313 u may (e.g.,each) be communicatively coupled with the port 314 i, theorthogonally-polarized elements 315 a of the radiating elements 313 incolumn 313 v may (e.g., each) be communicatively coupled with the port315 h, the orthogonally-polarized elements 315 b of the radiatingelements 313 in column 313 v may (e.g., each) be communicatively coupledwith the port 315 i, and so on. In one or more embodiments, thesub-elements in a dipole pair may be independent of (e.g., operatedindependently from) one another. For example, in certain embodiments,the sub-elements in a dipole pair may transmit and/or receiveindependently of one another. In various embodiments, each sub-elementin a dipole pair (and corresponding RF line and port) may operate inboth Tx and Rx directions (i.e., where Tx and Rx may occursimultaneously) and/or operate in multiple frequency bands (i.e., wherethere may be Tx and Rx occurring in each of multiple bands).

It is to be appreciated and understood that the antenna 310 may have aport/array configuration other than that shown, such as a configurationwith more or fewer radiating elements 313, more or fewer arrays ofradiating elements 313, and/or more or fewer ports.

As shown in FIG. 3A, the RPM 320 may include one or more polarizationshifters 330, a control unit 321 c, and one or more monitoring/detectionunits 321 d. In one or more embodiments, the polarization shifter(s)330, the control unit 321 c, and the monitoring/detection unit(s) 321 dmay be communicatively coupled with one another, with (e.g., each of)the radiating elements 313, and/or with various components of a radio340 (e.g., an RRH or RRU). As depicted, the RPM 320 may becommunicatively coupled to the radio 340 via analog/RF line(s) 314 m,314 n, 315 m, 315 n, etc.

In various embodiments, the polarization shifter(s) 330 of the RPM 320may be implemented as (or may include) one or more RF mechanicaldevices. In these embodiments, the RPM 320 may include a respective RFmechanical device for each column of radiating elements 313 (or for twoor more columns of radiating elements 313). In certain embodiments, theRF mechanical device may include hybrid coupler(s) andmechanically-adjustable dual simultaneous phase-shifting coupler(s)(e.g., as described in more detail below with respect to one or more ofFIGS. 5A-5C and 6).

The monitoring/detection unit(s) 321 d may be configured to performmeasurements on signals inputted to the polarization shifter(s) 330and/or signals outputted from the polarization shifter(s) 330. Incertain embodiments, the RPM 320 may include a respective polarizationshifter 330 and a respective monitoring/detection unit 321 d for eacharray of radiating elements 313. For instance, in the implementationshown in FIG. 3A, each of a first polarization shifter 330 and a firstmonitoring/detection unit 321 d may be coupled to each of the radiatingelements 313 in array 313 u, each of a second polarization shifter 330and a second monitoring/detection unit 321 d may be coupled to each ofthe radiating elements 313 in array 313 v, and so on. In this example,one sub-array of dipole elements in the array 313 u may be coupled tothe first polarization shifter 330 and to the first monitoring/detectionunit 321 d over one or more communication lines, and the otherorthogonal sub-array of dipole elements in the array 313 u may becoupled to the first polarization shifter 330 and to the firstmonitoring/detection unit 321 d over one or more other communicationlines. Continuing the example, one sub-array of dipole elements in thearray 313 v may be coupled to the second polarization shifter 330 and tothe second monitoring/detection unit 321 d over one or morecommunication lines, and the other orthogonal sub-array of dipoleelements in the array 313 v may be coupled to the second polarizationshifter 330 and to the second monitoring/detection unit 321 d over oneor more other communication lines, and so on. Further continuing theexample, in certain embodiments, output ports of the first polarizationshifter 330 may also be coupled to the first monitoring/detection unit321 d via respective communication lines, output ports of the secondpolarization shifter 330 may also be coupled to the secondmonitoring/detection unit 321 d via respective communication lines, andso on. In some alternate embodiments, a single monitoring/detection unit321 d may be coupled to multiple (e.g., some or all of the) arrays ofradiating elements 313 and/or to multiple (e.g., some or all of the)polarization shifters 330. In these embodiments, the singlemonitoring/detection unit 321 d may be coupled to some or all of theinput ports and output ports of the multiple polarization shifters 330via respective communication lines.

In exemplary embodiments, the control unit 321 c may be configured toreceive detection outputs from the monitoring/detection unit(s) 321 d(e.g., over any suitable interface, such as a Serial PeripheralInterface (SPI), a Recommended Standard interface (e.g., RS-232 or thelike), a Universal Serial Bus (USB) interface, and/or the like), processthe detection outputs to determine the optimal (or best) polarization(or angle) for each pair of orthogonal RF signals, and effectpolarization shifting of those RF signals according to the bestpolarization. Effecting polarization shifting may include causing, via amotor and drive assembly (e.g., described in more detail below withrespect to FIG. 7A), one or more components of one or more polarizationshifter(s) 330 that are disposed to intercept the orthogonal RF signalsto move so as to manipulate the orthogonal RF signals accordingly. Thepolarization shifting may result in a maximum in difference between theorthogonal RF signals associated with the dipole elements in onepolarization (e.g., +45 degrees) relative to signals associated with thedipole elements in the orthogonal polarization (e.g., −45 degrees)—e.g.,where one of the polarization-adjusted signals includes interference/PIMand the other of the polarization-adjusted signals does not include (orincludes only minimal) interference/PIM. In this way, the polarizationshifting may mimic physical rotation of the radiating elements, therebyenabling mitigation or avoidance of the interference/PIM—e.g., byselecting/using (e.g., only) the polarization-adjusted signal(s) thatinclude no (or minimal) interference/PIM.

It is to be understood and appreciated that the functionality of controlunit 321 c and the monitoring/detection unit(s) 321 d may be implementedin any desired number of boards. As an example, the control unit 321 cmay be implemented in a single board and the monitoring/detectionunit(s) 321 d may be implemented in multiple boards. As another example,the control unit 321 c may be implemented in a single board and themonitoring/detection unit(s) 321 d may also be implemented in a separatesingle board. As yet another example, the control unit 321 c may beimplemented in multiple boards and the monitoring/detection unit(s) 321d may be implemented in a single board. In certain embodiments, thecontrol functionality and monitoring/detection functionality may beimplemented in a single integrated board.

In various embodiments, the control unit 321 c (whether implemented as astandalone controller board or integrated with one or more otherdevices, such as the monitoring/detection unit(s) 321 d) may include avariety of components configured to provide the control functionalitydescribed herein. In one or more embodiments, the control unit 321 c mayinclude, among other components, one or more microcontrollers, one ormore analog-to-digital (A/D) converters, and/or hardware, firmware, or acombination of hardware and software for motor position management. Inexemplary embodiments, the control unit 321 c may be employed toconfigure the monitoring/detection unit(s) 321 d with desired settings,such as values for base frequencies, attenuation, and/or otherparameters.

Although FIG. 3A shows the RPM 320 as being a standalone device ormodule, in certain embodiments, some or all of thecomponents/functionality thereof (e.g., the polarization shifter(s) 330,the control unit 321 c, and/or the monitoring/detection unit(s) 321 d)may instead be implemented elsewhere, such as, for example, in theantenna 310 (e.g., FIG. 3B). In either implementation (whether as astandalone device or in the antenna 310), and where a dipole element,corresponding RF line, and corresponding port of the communicationssystem operate in both the Tx and Rx directions and/or operate inmultiple frequency bands, signal manipulation by the polarizationshifter(s) 330 may (e.g., equally) affect both the Tx and Rx signals onthat RF line across the multiple bands.

In alternate embodiments, the RPM 320 may be implemented/integrated inthe radio 340 (e.g., FIG. 3C), where polarization adjusting may beperformed for Tx only, for Rx only, or for both Tx and Rx as well asacross multiple bands in a case where a multi-band system is involved.Polarization adjustments (e.g., “rotation” angles) for Tx and Rx in agiven band may be the same, similar, or different, and the polarizationadjusting may be performed in the same manner, in a similar manner, ordifferently for Tx and Rx in the band. Tx in one band may also besubjected to polarization adjusting in the same, similar, or differentmanner (e.g., by the same or a different angle) as Tx in a differentband, and Rx in one band may also be subjected to polarization adjustingin the same, similar, or different manner (e.g., by the same or adifferent angle) as Rx in a different band. Where the radio 340 providesaccess to individual Tx and Rx across the different RF lines and/oracross the different frequency bands (thus obviating the need toconsider constraints relating to reciprocality and nonlinearitiesassociated with high power RF), the design of the RPM 320 may besimplified relative to the design of the components of the RPM 320 ineither FIG. 3A or FIG. 3B. As an example, certain RF circuitry and/orRF-based techniques (rather than RF mechanical device(s)) may beemployed to manipulate signals in an RF path. As another example,certain aspects of the control system may be additionallysimplified—e.g., motor(s) may or may not be needed, certain controlfunctionality of the control unit 321 d relating to motor control may ormay not be needed, and so on.

It is to be appreciated and understood that the quantities of thedevices/components shown in each of FIGS. 3A-3C are merely exemplary.That is, any of the systems shown in FIGS. 3A-3C may include any numberof (e.g., more or fewer) antennas 310, radiating elements 313, ports,analog/RF lines, RPMs 320, polarization shifter(s) 330, control units321 c, and/or monitoring/detection units 321 d. Furthermore, some ofthese devices/components may be combined with one another or with otherdevices/components.

FIGS. 4A-4E are block diagrams illustrating example polarizationshifters 430 a-430 e in accordance with various aspects describedherein. In various embodiments, each of the polarization shifters 430a-430 e may be the same as, may be similar to, or may otherwisecorrespond to any of the polarization shifters 330 of FIGS. 3A, 3B, and3C.

Referring to FIG. 4A, the polarization shifter 430 a may include a dualshifter 460 interfacing two 90° hybrid couplers 440 and 450. The 90°hybrid coupler 440 may receive inputs at “Port 1 in” and “Port 2 in”(which, in the system implementation of FIG. 3A, for example, maycorrespond to ports 314 h and 314 i, respectively, or ports 315 h, 315i, respectively). The 90° hybrid coupler 450 may provide outputs (which,in the system implementation of FIG. 3A, for example, may correspond tooutputs coupled to lines 314 m and 314 n, respectively, or outputscoupled to lines 315 m and 315 n, respectively). The dual shifter 460may include various components that, in conjunction with the two 90°hybrid couplers 440 and 450, are operable to effect polarizationshifting of signals (i.e., orthogonal RF signals at Port 1 in and Port 2in) in the RF (or analog) domain. The polarization adjusting may mimicphysical rotation of radiating elements, thereby enabling mitigation oravoidance of the interference/PIM—e.g., by selecting only the signal, oftwo orthogonal RF signals, that is (e.g., near) PIM-free. Exampleimplementations of the hybrid couplers and the dual shifter (which,together, provide a transfer function that is equivalent to the formulas202 p/202 r/202 q for angular rotation of orthogonal RF signals) aredescribed below with respect to FIGS. 5A-5D and 6.

In exemplary embodiments, each of the 90° hybrid couplers 440 and 450may be reciprocal or symmetrical devices, and thus, in embodiments wherethe Ports 1 and 2 operate in both Tx and Rx directions (i.e., where Txand Rx may occur simultaneously) and/or operate in multiple frequencybands (i.e., where there may be Tx and Rx occurring in each of multiplebands), each of the 90° hybrid couplers 440 and 450 may, on a givenline, input and output signals across one or more frequency bands. Forinstance, what is shown as “Port 1 in” for the 90° hybrid coupler 440may receive signals (Rx) and simultaneously output signals (Tx), what isshown as “Port 2 in” for the 90° hybrid coupler 440 may receive signals(Rx) and simultaneously output signals (Tx), and the two lines on theopposite end of the 90° hybrid coupler 440 may each receive and outputsignals (Rx and Tx).

With reference to FIG. 4B, the polarization shifter 430 b may be similarto the polarization shifter 430 a of FIG. 4A, but may be adapted toinclude one or more additional (e.g., independent) sets of the 90°hybrid couplers 440 and 450 and the dual shifter 460 for one or moreadditional pairs of input ports and corresponding pair(s) of outputports (e.g., for each additional column of radiating elements 313). Forinstance, the polarization shifter 430 b may be employed in a 4 Tx/Rxsystem. In systems where each port or RF line operates in multiple bands(e.g., 2 bands, 3 bands, etc.), the polarization shifter 430 b of FIG.4B should suffice since the interference/PIM to be addressed is likelyto impact the different bands in the same or a similar manner, and thusthe same polarization adjustment across all of the bands should beadequate. With reference to FIG. 4C, the polarization shifter 430 c maybe similar to the polarization shifter 430 b of FIG. 4B, but may beadapted for multi-band communications systems where each port or RF lineoperates in only a single band. With reference to FIG. 4D, thepolarization shifter 430 d may be similar to the polarization shifter430 b, but may be adapted for use with a 3 sector site (e.g., where 3antennas are mounted on a tower top or roof). With reference to FIG. 4E,the polarization shifter 430 e may be similar to the polarizationshifter 430 b, but where the additional sets of the 90° hybrid couplers440 and 450 and the dual shifter 460 are implemented in individualconstructions—i.e., a construction that includes multiple 90° hybridcouplers 440, a construction that includes multiple 90° hybrid couplers450, and a construction that includes multiple dual shifters 460. Here,one or more of the constructions may be implemented in multiple stages,and polarization adjusting may, via these stages, be selectivelyeffected on some or all of the RF lines (e.g., 2 of 4 RF lines or all 4RF lines) simultaneously.

It is to be appreciated and understood that the quantities of thecouplers, dual shifters, and lines/ports shown in each of FIGS. 4A-4Eare merely exemplary. That is, the polarization shifters in FIGS. 4A-4Emay each include any number of (e.g., more or fewer) hybrid couplers440, hybrid couplers 450, dual shifters 460, and lines/ports. Further,some of these devices/components may be combined with one another orwith other devices/components. For instance, a given 90° hybrid couplermay be formed in combination with a dual shifter 460. Furthermore, othertypes of couplers, such as 180° hybrid couplers (e.g., two or more 180°hybrid couplers along with a dual shifter 460), may alternatively beused or may be used in combination with one or more 90° hybrid couplersand dual shifters. Moreover, as described in more detail below, certainpolarization shifter embodiments may be configured with strip lines,which may be applicable to certain narrowband applications (e.g., wherethe bandwidth ratio relative to a center frequency can be up to 15%).However, other constructions applicable to wideband applications (e.g.,where the bandwidth ratio relative to a center frequency can be up to40%) are also possible. For instance, FIG. 4F is a block diagram of anexample, non-limiting embodiment of a (e.g., broadband) polarizationshifter 430 f that is similar to the polarization shifter 430 a, butthat is implemented using a dual shifter 490, one or more waveguides,cavities, or other structures 470, and one or more waveguides, cavities,or other structures 480. In certain embodiments, the dual shifter 490may be also implemented using one or more waveguides, cavities or otherstructures. In any case, various polarization shifter configurationssimilar to those shown in FIGS. 4B-4E may also be provided based on theconstruction shown in FIG. 4F. Additionally, the polarization shifter430 f may include any number of (e.g., more or fewer) waveguide(s) (orcavities/structures), dual shifters, and lines/ports than that shown.

FIGS. 5A-5D show views of various portions of an example, non-limitingembodiment of a polarization shifter 530 in accordance with variousaspects described herein. In various embodiments, the polarizationshifter 530 may be the same as, may be similar to, or may otherwisecorrespond to the polarization shifter 430 a of FIG. 4A, or may be thesame as, may be similar to, or may otherwise correspond to a portion ofany of the polarization shifters 430 b, 430 c, 430 d, and 430 e of FIGS.4B-4E. As shown in FIG. 5A, the polarization shifter 530 may include abottom (or lower) substrate 530 b, a top (or upper) substrate 530 t, anda (e.g., thin) dielectric layer 530 d disposed between the twosubstrates 530 b and 530 t.

The bottom substrate 530 b may include two transmission lines 566 c and566 d disposed thereon—i.e., on an upper surface of the bottom substrate530 b. Each of the transmission lines 566 c and 566 d may be amicrostrip or the like composed of conductive material, and may have oneor more curved portions. FIG. 5D is a perspective view of thetransmission line 566 d disposed on the bottom substrate 530 b.

Referring to FIG. 5A, the top substrate 530 t may include twotransmission lines 568 x and 568 y disposed thereunder—i.e., on anundersurface of the top substrate 530 t. Each of the transmission lines568 x and 568 y may be a microstrip or the like composed of conductivematerial, and may have one or more curved portions. In variousembodiments, the dielectric layer 530 d may serve to couple thetransmission lines 568 x and 568 y with the transmission lines 566 c and566 d.

In various embodiments, each of the substrates 530 b and 530 t may be aprinted circuit board (PCB) or the like. In one or more embodiments, thedielectric layer 530 d may be composed of polytetrafluoroethylene (PTFE)or the like (e.g., Teflon tape or film), and may function as a lowfriction insulator/buffer between the bottom substrate 530 b and the topsubstrate 530 t. Although the bottom substrate 530 b, the top substrate530 t, and the dielectric layer 530 d are each shown to have a specificshape and particular dimensions, each of these components can have anyother shape or combination of shapes and can have any suitabledimensions depending on design/performance parameters. For instance, anarea of the top substrate 530 t may be the same as, larger than, orslightly smaller than an area of the bottom substrate 530 b.

In exemplary embodiments, the dielectric layer 530 d may be coupled(e.g., adhesively fixed) to an undersurface of the top substrate 530 t,and may have an area that is larger than an area of the top substrate530 t. In some alternate embodiments, the dielectric layer 530 d may becoupled (e.g., adhesively fixed) to an upper surface of the bottomsubstrate 530 b. In other alternate embodiments, there may be twodielectric layers 530 d—one layer 530 d coupled (e.g., adhesively fixed)to an undersurface of the top substrate 530 t and another layer 530 dcoupled (e.g., adhesively fixed) to an upper surface of the bottomsubstrate 530 b, which may further reduce friction between the twosubstrates.

As shown in FIG. 5A, the polarization shifter 530 may include a pair ofhybrid couplers 540 and 550 disposed on the bottom substrate 530 b. Inexemplary embodiments, each of the hybrid couplers 540 and 550 may be a90° hybrid coupler (e.g., a square or near square structure with aboutequal sides, where each side may correspond to about one signalwavelength). In alternate embodiments, one or more of the hybridcouplers 540 and 550 may be a different type of coupler, such as a 180°hybrid coupler.

As depicted, the hybrid coupler 540 may include ports 540 a, 540 b, 540h, and 540 j, and the hybrid coupler 550 may include ports 550 a, 550 b,550 i, and 500 k. Each of the ports 540 a, 540 b, 540 h, 540 j, 550 a,550 b, 550 i, and 550 k may be reciprocal or duplex in that it cansimultaneously function as both an input port and an output port. Eachof the hybrid couplers 540 and 550 may be configured to combine portionsof signals at input ports and provide combined signals at output ports.For example, where signals s₁ and s₂ are respectively fed to inputs 540a and 540 b of hybrid coupler 540, the hybrid coupler 540 may combine aportion of signal s₁ and a portion of signal s₂ (rotated by 90°) foroutput at output 540 h (e.g., to portion 566 h of the transmission line566 c) and may combine a portion of signal s₂ and a portion of signal s₁(rotated by 90°) for output at output 540 j (e.g., to portion 566 j ofthe transmission line 566 c). Continuing the example, the hybrid coupler550 may combine a portion of a resulting signal at input 550 i and aportion of a resulting signal at input 550 k (rotated by 90°) for outputat output 550 a and may combine a portion of the resulting signal atinput 550 k and a portion of the resulting signal at input 550 i(rotated by 90°) for output at output 550 b. Each of the hybrid couplers540 and 550 may thus take an input on one port and provide an even powersplit thereof on two output ports with a 90° phase shift between them.

In the implementation described above with respect to FIG. 3A, the ports540 a and 540 b of the hybrid coupler 540 may be communicatively coupledto a set of ports of the antenna 310 (e.g., ports 314 h and 314 i orports 315 h and 315 i), and the ports 550 a and 550 b of the hybridcoupler 550 may be coupled to a set of lines interfacing the RPM 320 andthe radio 340 (e.g., lines 314 m and 314 n or lines 315 m and 315 n).

In the implementation shown in FIG. 3B (where the RPM 320 isalternatively included in the antenna 310), the ports 540 a and 540 b ofthe hybrid coupler 540 may be communicatively coupled to an array ofradiating elements 313 (e.g., a feed network of array 313 u or a feednetwork of array 313 v), and the ports 550 a and 550 b of the hybridcoupler 550 may be coupled to a set of ports of the antenna 310 (e.g.,ports 314 h and 314 i or ports 315 h and 315 i).

As depicted in FIG. 5A, the transmission lines 568 x and 568 y may atleast partially overlap the transmission lines 566 c and 566 d. Byvirtue of the overlapping as well as the close proximity of thetransmission lines 568 x and 568 y and the transmission lines 566 c and566 d, portions of the transmission lines 566 c and 566 d may be coupledto one another to form a coupled line 557 a in the upper half of theconstruction and a coupled line 557 b in the lower half of theconstruction (i.e., yielding a dual shifter 560). As shown, the coupledline 557 a may include the transmission line 568 x, a portion 566 h ofthe transmission line 566 c, and a portion 566 i of the transmissionline 566 d; and the coupled line 557 b may include the transmission line568 y, a portion 566 j of the transmission line 566 c, and portion 566 kof the transmission line 566 d. Each of the coupled lines 557 a and 557b may behave as a line with minimal to no additional losses as comparedto a single transmission line of the same length. In other words, mostor all of the signal energy on the coupled line 557 a may be transmittedthrough the coupled line 557 a with little to none of the energy beinglost or reflected, and similarly, most or all of the signal energy onthe coupled line 557 b may be transmitted through the coupled line 557 bwith little to none of the energy being lost or reflected.

In certain embodiments, the transmission lines 566 c, 566 d, 568 x, and568 y may be designed and constructed (with select shapes, curvature,dimensions, etc.) such that impedance of each of the coupled lines 557 aand 557 b is kept matched regardless of the “rotational” position for anoutput line portion or regardless of a length of overlap of the“rotated” output line portion and the corresponding input line portion.The shapes and/or dimensions of the transmission lines 566 c, 566 d, 568x, and 568 y may also be defined to minimize insertion losses and/orreturn losses.

Although not shown, in certain embodiments, the two coupled lines 557 aand 557 b may be separated by one or more ground strips (e.g., viaplated through-holes in between the coupled lines 557 a and 557 b) inorder to improve isolation between the two signal polarizations.

In exemplary embodiments, the top substrate 530 t may be configured tomove relative to the bottom substrate 530 b in the +X/−X direction. Byvirtue of the partial overlapping of the transmission lines 568 x and568 y on the transmission lines 566 c and 566 d as well as thedimensions and shapes of the transmission lines 568 x and 568 y (e.g.,U-shapes) and the transmission lines 566 c and 566 d (e.g., portionsthereof being parallel to one another), relative movement of the topsubstrate 530 t and the bottom substrate 530 b—resembling the slidingin/out of two trombones (hence, the descriptive “double trombone” phaseshifter device)—may affect or change the coupled lines 557 a and 557 band provide double simultaneous phase shifting effects to RF signalscarried by these coupled lines. For instance, where signals s₁ and s₂are respectively fed to inputs 540 a and 540 b of hybrid coupler 540,the difference in phase between the combined s₁, s₂ signal carried byportion 566 h of the transmission line 566 c and the combined s₁, s₂signal carried by portion 566 i of the transmission line 566 d maychange based on movement of the top substrate 530 t relative to thebottom substrate 530 b, and the difference in phase between the combineds₁, s₂ signal carried by portion 566 j of the transmission line 566 cand the combined s₁, s₂ signal carried by portion 566 k of thetransmission line 566 d may similarly change based on movement of thetop substrate 530 t relative to the bottom substrate 530 b. Changes inthese phases may result in polarization shifting of the input signals s₁and s₂ that mimics physical rotation of radiating element(s). In variousembodiments, the amplitudes of signals on the coupled lines 557 a and557 b may change in a manner similar to the cosine and sine operationsin equations 202 q/202 r of FIGS. 2C/2D—e.g., where movement of the topsubstrate 530 t in the +X direction in FIG. 5A may cause there to bemore signal energy on the coupled line 557 a than on the coupled line557 b, and thus a signal at the (e.g., output) port 550 a may have alarger amplitude than a signal at the (e.g., output) port 550 b.

FIG. 5A shows the top substrate 530 t in a centered position relative tothe bottom substrate 530 b—e.g., in a zero or neutral position wherethere is a symmetrical overlapping of the transmission lines 568 x and568 y with the transmission lines 566 c and 566 d, and thus symmetrybetween the coupled lines 557 a and 557 b. In exemplary embodiments,movement of the top substrate 530 t may be made in increments that eachcorresponds to a certain angular increment or “rotation”—a 1 degreerotation per increment, 2.25 degree rotation per increment, a 3 degreerotation per increment, a 5.625 degree rotation increment, etc.—oforthogonal signals that, together, span a 90-degree range (correspondingto orthogonality of the signals). Movement of the top substrate 530 t toa “maximum” position of the top substrate 530 t in a +X direction (FIG.5B) (i.e., full asymmetry between the coupled lines 557 a and 557 b inone direction) may correspond to a +45 degree rotation, and movement ofthe top substrate 530 t to a “maximum” position of the top substrate 530t in a −X direction (FIG. 5C) (i.e., full asymmetry between the coupledlines 557 a and 557 b in the other direction) may correspond to a −45degree rotation. In this way, the two polarizations of orthogonal RFinput signals may be rotated together by the same amount by mechanicallymoving the top substrate 530 t. That is, changing the position of thetop substrate 530 t may effect polarization adjusting (or a manipulationthat is mathematically similar to phase rotation) of orthogonal RFsignals (e.g., angle θ and thus the “weights” in equations 202 q and 202r of FIGS. 2C and 2D) that mimics the physical rotation of radiatingelements. In the presence of PIM or interference, there will be anoptimal (or best) top substrate 530 t position in which one of theorthogonal RF signals will be “rotated” such that it is (e.g., near)PIM/interference-free and the other orthogonal RF signal will be“rotated” such that it includes most or all of the PIM/interference.

It is to be appreciated and understood that the shapes and/or dimensionsof the transmission lines 566 c, 566 d, 568 x, and 568 y may be definedto yield any desired extent of overlap between coupled lines when thepolarization shifter 530 is operated. Thus, in certain embodiments,movement of the top substrate 530 t may or may not result in the sameoverlap or coupling between the transmission line 568 x and thetransmission lines 566 c and 566 d (e.g., transmission line 568 x mayoverlap transmission line 566 c more or less than transmission line 566d), and may or may not result in the same overlap or coupling betweenthe transmission line 568 y and the transmission lines 566 c and 566 d(e.g., transmission line 568 y may overlap transmission line 566 c moreor less than transmission line 566 d). In exemplary embodiments, theshapes and/or dimensions of the transmission lines 566 c, 566 d, 568 x,and 568 y may be defined or adjusted such that the angle θ of rotationof orthogonal RF signals is proportional to a distance of travel of thetop substrate 530 t from its center/neutral position.

Reference number 539 of FIG. 5A shows a partial cross-sectional view ofthe portion of the polarization shifter 530 taken along line A-A. Inexemplary embodiments, the bottom substrate 530 b may be (e.g., a partof) a ground plane of the antenna 310.

While the partial cross-sectional view 539 of FIG. 5A shows the top andbottom substrates 530 t and 530 b and the dielectric layer 530 d asbeing separated from one another based on the dimensions of the varioustransmission lines, in certain embodiments, some or all of thetransmission lines may be at least partially embedded in a surface ofthe respective substrate. In these embodiments, the top and bottomsubstrates 530 t and 530 b may be in contact with one another, separatedonly by the dielectric layer 530 d.

Although not shown, in some embodiments, one or more of the transmissionlines 566 c and 566 d may further extend (or may couple with one or moreother lines that extend) beyond the portion of the bottom substrate 530b shown. In one or more embodiments, the transmission lines 566 c and566 d may be coupled to the control unit 321 c and/or themonitoring/detection unit 321 d (e.g., via respective connection lines).

In various embodiments, a respective polarization shifter 530 may becoupled to each column of radiating elements of an antenna. In theexample implementation of the antenna 310 shown in FIG. 3A, forinstance, a first polarization shifter 530 may be coupled to the array313 u of radiating elements (e.g., ports 540 a and 540 b of the firstpolarization shifter 530 may be respectively coupled to ports 314 h and314 i), and a second polarization shifter 530 may be coupled to thearray 313 v of radiating elements (e.g., ports 540 a and 540 b of thesecond polarization shifter 530 may be respectively coupled to ports 315h and 315 i).

FIG. 6 shows views of an example, non-limiting embodiment of apolarization shifter 630 in accordance with various aspects describedherein. In various embodiments, the polarization shifter 630 may be thesame as, may be similar to, or may otherwise correspond to thepolarization shifter 430 a of FIG. 4A, or may be the same as, may besimilar to, or may otherwise correspond to a portion of any of thepolarization shifters 430 b, 430 c, 430 d, and 430 e of FIGS. 4B-4E. Inone or more embodiments, the polarization shifter 630 may be similar tothe polarization shifter 530 (various aspects of the polarizationshifter 530 may be the same for the polarization shifter 630), but maybe mechanically adjustable in a rotational manner (rather than in alinear manner). As shown in FIG. 6, the polarization shifter 630 includea bottom (or lower) substrate 630 b, a top (or upper) substrate 630 t,and a (e.g., thin) dielectric layer 630 d disposed between the twosubstrates 630 b and 630 t.

As shown in FIG. 6, the polarization shifter 630 may include a pair ofhybrid couplers 640 and 650 disposed on the bottom substrate 630 b. Inexemplary embodiments, each of the hybrid couplers 640 and 650 may be a90° hybrid coupler similar to that of the polarization shifter 530.However, a portion of each of the hybrid couplers 640 and 650 may beadapted to include or couple to a curved (e.g. semicircular)transmission line—i.e., transmission lines 666 c and 666 d. Each of thetransmission lines 666 c and 666 d may be a microstrip or the likecomposed of conductive material.

As shown in FIG. 6, the top substrate 630 t may include two transmissionlines 668 x and 668 y disposed thereunder—i.e., on an undersurface ofthe top substrate 630 t. Each of the transmission lines 668 x and 668 ymay be a microstrip or the like composed of conductive material, and mayhave one or more curved portions.

Although the bottom substrate 630 b, the top substrate 630 t, and thedielectric layer 630 d are each shown to have a specific shape andparticular dimensions, each of these components can have any other shapeor combination of shapes and can have any suitable dimensions dependingon design/performance parameters. For instance, an area of the topsubstrate 630 t may be the same as, larger than, or slightly smallerthan an area of the bottom substrate 630 b.

As depicted in FIG. 6, the transmission lines 668 x and 668 y may atleast partially overlap the transmission lines 666 c and 666 d. Byvirtue of the overlapping as well as the close proximity of thetransmission lines 668 x and 668 y and the transmission lines 666 c and666 d, portions of the transmission lines 666 c and 666 d may be coupledto one another to form a coupled line 657 a in the upper half of theconstruction and a coupled line 657 b in the lower half of theconstruction (i.e., yielding a dual shifter 660). As shown, the coupledline 657 a may include the transmission line 668 x, a portion of thetransmission line 666 c, and a portion of the transmission line 666 d;and the coupled line 657 b may include the transmission line 668 y, aportion of the transmission line 666 c, and portion of the transmissionline 666 d.

In exemplary embodiments, the top substrate 630 t may be configured tomove rotationally relative to the bottom substrate 630 b in the XYplane. By virtue of the partial overlapping of the transmission lines668 x and 668 y on the transmission lines 666 c and 666 d as well as thedimensions and shapes of the transmission lines 668 x and 668 y (e.g.,arch or semicircular shapes) and the transmission lines 666 c and 666 d,rotational movement of the top substrate 630 t relative to the bottomsubstrate 630 b may affect or change the coupled lines 657 a and 657 band provide double simultaneous phase shifting effects to RF signalscarried by these coupled lines similar to that described above withrespect to the polarization shifter 530. Changes in these phases mayresult in polarization shifting of input signals that mimics physicalrotation of radiating element(s).

FIG. 6 shows the top substrate 630 t in a particular orientationrelative to the bottom substrate 630 b—e.g., in a zero or neutralposition where there is a symmetrical overlapping of the transmissionlines 668 x and 668 y with the transmission lines 666 c and 666 d, andthus symmetry between the coupled lines 657 a and 657 b. In exemplaryembodiments, rotational movement of the top substrate 630 t may be madein increments that each corresponds to a certain angular increment or“rotation”—a 1 degree increment, 2.25 degree increment, a 3 degreeincrement, a 5.625 degree rotation, etc.—of orthogonal signals that,together, span a 90-degree range (corresponding to orthogonality of thesignals). Movement of the top substrate 630 t to a “maximum” position ofthe top substrate 630 b in a clockwise direction may correspond to a +45degree rotation, and rotational movement of the top substrate 630 t to a“maximum” position of the top substrate 630 b in a counterclockwisedirection may correspond to a −45 degree rotation. In this way, the twopolarizations of orthogonal RF input signals may be rotated together bythe same amount by mechanically rotating the top substrate 630 b. Thatis, changing the position of the top substrate 630 b may effectpolarization adjusting (or a manipulation that is mathematically similarto phase rotation) of orthogonal RF signals (e.g., angle θ and thus the“weights” in equations 202 q/202 r of FIGS. 2C/2D) that mimics thephysical rotation of radiating elements. In the presence of PIM orinterference, there will be an optimal (or best) top substrate 630 tposition or orientation in which one of the orthogonal RF signals willbe “rotated” such that it is (e.g., near) PIM/interference-free and theother orthogonal RF signal will be “rotated” such that it includes mostor all of the PIM/interference.

Reference number 639 of FIG. 6 shows a partial cross-sectional view ofthe portion of the polarization shifter 630 taken along line B-B. Inexemplary embodiments, the bottom substrate 630 b may be (e.g., a partof) a ground plane of the antenna 310.

In exemplary embodiments, mechanical movement of a polarization shifter(e.g., the polarization shifter 530 or the polarization shifter 630) maybe achieved via control of a motorized device and a drive assembly. FIG.7A is a block diagram of an example, non-limiting embodiment of apolarization shifter 730 in operation with a motor 702 and a driveassembly 704 in accordance with various aspects described herein.

In various embodiments, the polarization shifter 730 may be the same as,may be similar to, or may otherwise correspond to the polarizationshifter 530 of FIG. 5A, or may be the same as, may be similar to, or mayotherwise correspond to the polarization shifter 630 of FIG. 6. Invarious embodiments, the motor 702 may be communicatively coupled with acontrol unit, such as any of the control units 321 c of FIGS. 3A-3C,over any suitable interface—e.g., a Serial Peripheral Interface (SPI), aRecommended Standard interface (e.g., RS-232 or the like), a UniversalSerial Bus (USB) interface, and/or the like. The motor 702 may beconfigured to transmit force(s) to the drive assembly 704 based oncommands received from the control unit 321 c.

An RPM may include any desired number of motors 702 and drive assemblies704. For instance, in some embodiments, an RPM 220 or 320 may include amotor 702 and a drive assembly 704 for each polarization shifter, suchas one motor 702 and one drive assembly 704 for a first polarizationshifter 530, another motor 702 and another drive assembly 704 for asecond polarization shifter 530, and so on. As an example, a respectivemotor 702 and a respective drive assembly 704 may be arranged for eachpair of RF lines in a 4 Tx/Rx system (e.g., FIG. 4B). In otherembodiments, an RPM 220 or 320 may include a single motor 702 and one ormore drive assemblies 704 coupled to the various polarization shifters.In these embodiments, the single motor 702 may include, or may beintegrated with, one or more (e.g., electronic) gears and/or latches,such as relay(s), contactor(s), solenoid(s), and/or the like, to enablediffering linear/rotational movements of components/substrates of thepolarization shifters. In certain embodiments, the control unit 321 c,the monitoring/detection unit(s) 321 d, and one or more motors 702 maybe implemented in a single, integrated construction.

FIG. 7B is a perspective view of an example, non-limiting embodiment ofa motor 712 and a drive assembly 714 adapted to provide linear forces inaccordance with various aspects described herein. As shown in FIG. 7B,the motor 712 may be configured to transmit forces to the drive assembly714 via a threaded rod 714 r. The drive assembly 714 may include acontrol rod 714 d and a carriage/carrier 714 c. The carriage 714 c maybe threadably coupled to the threaded rod 714 r, which may be secured toa bracket 714 b. Rotation of the motor 712 (e.g., clockwise orcounterclockwise) may correspondingly turn the threaded rod 714 r, andthus the carriage 714 c, and cause the control rod 714 d to movelinearly with respect to the threaded rod 714 r. With a portion of thecontrol rod 714 d coupled to a component/substrate, such as a portion ofthe top substrate 530 t of the polarization shifter 530, linear movementof the control rod 714 d may impart linear force to the substrate 530 t(e.g., in the +X/−X directions shown in FIG. 5A) to thereby effectpolarization shifting/adjusting.

FIG. 7C is a perspective view of an example, non-limiting embodiment ofthe motor 712 and the drive assembly 714 adapted to provide rotationalforces in accordance with various aspects described herein. As shown inFIG. 7C, the drive assembly 714 may be adapted to include a slottedlever 714 v coupled to the control rod 714 d. A rotatable structure 714s may be coupled, at one end, to the slotted lever 714 v, and, atanother end, to a substrate, such as the top substrate 630 t of thepolarization shifter 630. Here, rotation of the motor 712 (e.g.,clockwise or counterclockwise) may correspondingly turn the threaded rod714 r, and thus the carriage 714 c, and cause the control rod 714 d tomove linearly with respect to the threaded rod 714 r. With the controlrod 714 d coupled to a slot 714 o of the slotted lever 714 v, movementof the control rod 714 d may impart rotational force to the rotatablestructure 714 s and thus the top substrate 630 t (e.g., in the XY planeshown in FIG. 6) to thereby effect polarization shifting/adjusting.

FIG. 8A is a block diagram of an exemplary, non-limiting embodiment of afunctional architecture of the control unit 321 c in accordance withvarious aspects described herein. In exemplary embodiments, the controlunit 321 c may be configured to obtain/read power level(s) of orthogonalsignals from the monitoring/detection unit(s) 321 d, calculate averagepower value(s), analyze the calculations, select an optimal (or best)component/substrate position (e.g., the best linear position of the topsubstrate 530 t of the polarization shifter 530 or the best rotationalposition of the top substrate 630 t of the polarization shifter 630)based on the analysis, and/or control motion of the motor(s) 702 tofacilitate interference/PIM mitigation or avoidance.

In some embodiments, the control unit 321 c may be equipped with anoperating system (OS) 808 configured to manage power state (e.g., idle,active, etc.), memory allocation, software updates, system and defaultdata configuration, interrupt management and time-sharing execution oftasks, etc. In certain embodiments, the OS may be configured to manageand control various (e.g., modular) functionality relating to the RPM220 or 320. Example functionality may include shifter communicationfunctionality 810, monitoring/detection unit communication functionality812, motor driver and positioning functionality 814, and/ormonitoring/detection sampling/calculation functionality 816. It is to beappreciated and understood that the various functionality may beimplemented in any suitable manner (in a modular manner or a non-modularmanner), and may be used or combined with other additional functionalitynot shown.

In various embodiments, the shifter communication function 810 mayprovide the necessary functions for exchanging messages with an externalsource, such as, a user computing device, an automated system, and/oranother device/system to configure/manage orthogonal signal powerreadings/measurements, monitor system performance, etc. The function 810may employ any suitable communication protocol, such as, for example,Transmission Control Protocol/Internet Protocol (TCP/IP), RS485 serial,User Datagram Protocol (UDP), and/or the like.

In various embodiments, the monitoring/detection unit communicationfunction 812 may provide the necessary functions for exchanging messageswith the monitoring/detection unit(s) 321 d to configure/manage detectorsettings, receive detector errors, obtain power readings/measurements,etc. The function 812 may employ any suitable communication protocol,such as, for example, USB, SPI, RS485 serial, and/or the like.

In various embodiments, the motor driver and positioning function 814may be configured to control rotary motion of the motor(s) 702, speed ofthe motor(s) 702, and/or displacement or distance of travel of themotor(s) 702. Positioning functionality (or circuitry) may monitor andvalidate motor movements relative to desired component/substratepositions.

In various embodiments, the monitoring/detection sampling/calculationfunctionality 816 may sample RF voltage detection outputs provided bythe monitoring/detection unit(s) 321 d, calculate the optimal (e.g.,best) component/substrate position(s), and provide instructions to themotor driver and positioning function 814 to move the motor(s) 702accordingly.

The following is an overview of an exemplary implementation formitigating or avoiding PIM or interference. PIM, for instance, generallydoes not have random characteristics, but is rather highly-directionallypolarized in space. Depending on the orientation of the PIM source, thepolarizations of orthogonal RF signals may be shifted or adjusted tofacilitate avoidance of the PIM. For example, in the RPM 220, for agiven pair of orthogonal RF signals, power measurements (e.g., peak,average, and/or root mean square) may be made for each signal in thepair, and a ratio of the two measurements may be calculated to identifythe PIM. Where there is no PIM or interference in the signals, themeasurements are expected to be essentially equal. However, in thepresence of PIM or interference, there will be an optimal (or best)“rotation” (or orientation) of the orthogonal RF signals where one ofthe orthogonal signals becomes/is (e.g., near) PIM/interference-free andthe other orthogonal signal includes most or all of thePIM/interference. In implementations of the RPM 220 or 320, acomponent/substrate (e.g., the top substrate 530 t of the polarizationshifter 530 or the top substrate 630 t of the polarization shifter 630)can be incrementally moved to occupy different positions in a continuousor sequential manner, and signal power measurements may be made at eachof the incremental steps to identify the optimal (or best)component/substrate position.

In exemplary embodiments, identifying an angle of incominginterference/PIM enables effective mitigation or avoidance thereof. FIG.8B illustrates a crossed-dipole radiating element and an incoming signalin accordance with various aspects described herein. Orthogonal RFsignals received by each dipole element of the dipole pair may beinputted to the RPM 220 or 320 (and, e.g., detected by amonitoring/detection unit 321 d). As depicted in FIG. 8B, relativepolarization angle α is the angle between the incominglinearly-polarized signal and one of the dipole elements (and thus theangle relative to one of the orthogonal signals). The power of each ofthe orthogonal signals may be proportional to both an amplitude A of theincoming signal and the angle α, and therefore, may not be effectivelyused to determine the angle α unless the amplitude A is known:P(−45)=A*sin(α); andP(+45)=A*cos(α).In fact, even if multiple power measurements of the incoming signal aretaken at different polarization angles, it would still be difficult toaccurately determine the smallest angle α, since the amplitude A of thesignal might change due to varying traffic during the measurementperiod. However, by (e.g., simultaneously) measuring the signal power ofboth orthogonal signals, and computing the ratio of the power levels,the result will not be affected by the signal amplitude A, but (e.g.,only) by the polarization angle:P(+45)/P(−45)=A*cos(α)/A*sin(α)=cot(α).Therefore, the largest power ratio will indicate the smallest angle αregardless of signal amplitude A. Since, for linearly-polarized signals,the angle α is fairly constant over time and amplitude variations,different kinds of power measurements may be made (such as root meansquare (RMS), peak, instantaneous, average, or a combination of one ormore of these kinds of power measurements), so long as bothpolarizations are measured simultaneously and using the same measurementmethod. When measuring the power of a communication signal in the fieldenvironment, care must generally be taken to detect only the signal ofinterest and avoid contributions from any overlapping or adjacentsignals. A narrow bandwidth power detector may be employed in variousembodiments to enable such selective detection.

FIG. 8C is a block diagram of an exemplary, non-limiting implementationof the monitoring/detection unit 321 d in accordance with variousaspects described herein. In exemplary embodiments, the implementation822 d may be a polarization alignment detector system/circuit, or moreparticularly, a narrow bandwidth power detector 822 d, that enablesdifferential power measurements to be made for determining the relativepolarization angle α.

In various embodiments, the narrow bandwidth power detector 822 d mayinclude a (e.g., standard commercially available) power detector 822 pconfigured to measure power only over a selected, narrow portion of thesignal without external interference. Because RF power detectorsgenerally do not discriminate between signals in the frequency spectrum(they detect a very wide range of frequencies, such as severalGHz-wide), the implementation 822 d may include a high rejection, narrowbandwidth band-pass filter 822 f in front of the power detector 822 p toprovide a narrow detection range. To add frequency selectivity to thesystem, the narrow bandwidth band-pass filter 822 f may be designed orchosen to be selective in the intermediate frequency (IF) band, and adown-converter mixer 822 m may be utilized to translate the RF frequencyof interest to the pass-band of the filter 822 f. Adjustments to thelocal oscillator (LO) frequency of the down-converter mixer 822 m mayenable narrow bandwidth power measurements to be made at differentfrequencies. As the power detector 822 p is configured to operate acrossthe same narrow bandwidth of the band-pass filter 822 f, the overallsystem/circuit 822 d provides suitable stability.

PIM occurs when two or more signals are present in passive (mechanical)components of a wireless system. Some examples of mechanical componentsinclude antennas, cables, and connectors. The signals can mix ormultiply with each other to generate other signals that impact theoriginal intended signal. This results in degraded cellular receiverperformance and can negatively impact voice calls and data transmissionquality for end users. The bandwidth of a PIM signal is much larger thanthe bandwidth of original, intended signals. As an example, for two 10MHz signals, the third order PIM would be 30 MHz wide. As a result, theinterfering PIM signal, created by two high power DLs, would always havea larger bandwidth than the affected UL, and there would be regions ofthe frequency spectrum where only the PIM signal is present, such as theguard bands between assigned communication bands. Performing narrow bandmeasurements in those regions using power detection method(s) describedabove will provide information regarding the polarization of only thePIM signal. Furthermore, if measurements are performed at two differentfrequencies A and B within the expected bandwidth of the PIM and outsideof the frequency range of other known signals, both results shouldindicate the same polarization since they represent samples of the samePIM signal. FIGS. 8D and 8E illustrate identification of PIMpolarization in accordance with various aspects described herein.

As briefly described above, the motor 702 may control movement of acomponent/substrate (e.g., the top substrate 530 t of the polarizationshifter 530 or the top substrate 630 t of the polarization shifter 630).In various embodiments, the motor 702 may control movement of acomponent/substrate in increments or steps. As an example, for thepolarization shifter 530, the motor 702 may control linear movement ofthe top substrate 530 t in increments (e.g., 1 mm increments, 2 mmincrements, etc.), where each increment may correspond to a certainangular increment or “rotation”—a 1 degree increment, a 2.25 degreeincrement, a 3 degree increment, a 5.625 degree increment, etc.—oforthogonal signals that, together, span a 90-degree range (correspondingto orthogonality of the signals). As another example, for thepolarization shifter 630, the motor 702 may control rotational movementof the top substrate 630 t in increments (e.g., 1 degree increments, 2degrees increments, etc.), where each such increment may correspond to acertain angular increment or “rotation”—a 1 degree increment, 2.25degree increment, a 3 degree increment, a 5.625 degree increment,etc.—of orthogonal signals that, together, span a 90-degree range(corresponding to orthogonality of the signals). In any case, powerreadings/measurements may then be performed (e.g., in a looped fashion)for such positions. The number of positions may vary depending onreading granularity needed, design parameters, and/or otherconsiderations.

For purposes of illustration, measurements for sixteen (16) positions ofa component/substrate are described below, but it should be appreciatedand understood that the position loop may be divided in more or fewerpositions, such as 40 positions, 32 positions, 13 positions, 8positions, etc. In one or more embodiments, the control unit 321 c mayconfigure the monitoring/detection unit 321 d with desired settings,such as, for example, base frequency (e.g., Freq. A, B, etc.),attenuation, and/or other pertinent working data, and may then cause themotor 702 to drive the drive assembly 704 such that thecomponent/substrate moves to the first of 16 positions. Theconfiguration and/or power reading/measurement process may be initiatedor triggered in any suitable manner, such as via external input (e.g.,from a user device, base station, etc.) and/or based upon a conditionbeing satisfied (e.g., time of day being reached, power threshold(s)being met, expiration of an initiated timer, etc.). In variousembodiments, voltage(s) of orthogonal RF signals may be detected by themonitoring/detection unit 321 d and obtained/read by the control unit321 c. Here, a particular number of (e.g., substantially) simultaneousreadings of voltage may be performed for the first position, and suchreadings may be repeated (e.g., looped) a certain number of times forthe first position. For purposes of illustration, the particular numberof (e.g., substantially) simultaneous readings may be set to three (3)and the number of repetitions of such readings may be set to give (5),but it is to be appreciated and understood that the control unit 321 cmay perform any other numbers of (e.g., substantially) simultaneousreadings and repetitions of such readings for each position. In one ormore embodiments, the (e.g., substantially) simultaneous readings may beperformed using multiple analog-to-digital (A/D) converters of thecontrol unit 321 c that may be coupled to the monitoring/detection unit321 d and configured to read analog voltage inputs for respectivesignals. The control unit 321 c may store the voltage inputs in a datastructure—e.g., a table in a memory included in or accessible to thecontrol unit 321 c. For instance, the control unit 321 c may store eachof five sets of three (e.g., substantially) simultaneous voltagereadings in a temporary table, resulting in a 3×5 table. FIG. 9A showsan example orthogonal signal voltage reading table 920 in accordancewith various aspects described herein.

In various embodiments, the control unit 321 c may cause (via control ofthe motor 702) the component/substrate to move to each position, and mayrepeat the five sets of three (e.g., substantially) simultaneous voltagereadings. The control unit 321 c may then calculate average power levelsbased on the sets of (e.g., substantially) simultaneous voltagereadings, and store the average power levels in a data structure—e.g.,another table in the memory. FIG. 9B shows an examplecomponent/substrate position table 922 in accordance with variousaspects described herein. Here, the component/substrate position table922 may include average voltages determined based on the table 920 ofFIG. 9A for 16 positions and two different frequencies A and B.

In one or more embodiments, the control unit 321 c may calculate theaverages as follows:

Average (RF_Det_Voltage, position_1)=average of the voltages in row 920a in table 920 of FIG. 9A=average (2.6, 2.5, 2.4, 2.6, 2.7)=2.56;

Average (RF_Det_Voltage, position_2)=average of the voltages in row 920b in table 920 of FIG. 9A=average (1.2, 1.0, 1.3, 1.1, 1.3)=1.18;

Average (RF_Det_Voltage, position_3)=average of the voltages in row 920c in table 920 of FIG. 9A=average (2.3, 2.2, 2.4, 2.4, 2.4)=2.34; and soon.

In various embodiments, the above-described process may be repeated fora different frequency (e.g., Freq. B different from Freq. A). In one ormore embodiments, the control unit 321 c may perform an analysis of theaverage voltage readings and identify an optimal (or best) position forthe component/substrate based on the analysis.

In various embodiments, the control unit 321 c may calculate, for eachposition and each frequency (e.g., Freq. A and B), an absolute value“ABS” based on the corresponding measured voltages. Each absolute valuemay be determined in a variety of manners, such as, for example, thefollowing:

Component/Substrate (position_no, Freq_A_ABS)=(ABS(Component/Substrate(position_no, 1)−Component/Substrate (position_no,2)+ABS(Component/Substrate (position_no, 3)−2.5)))/2, where, forposition 1 and Freq. A in the table 922 of FIG. 9B, the absolute value“ABS”=(ABS(2.56−1.18+ABS(2.34−2.5)))/2=0.77;

Component/Substrate (position_no, Freq_B_ABS)=(ABS(Component/Substrate(position_no, 4)−Component/Substrate (position_no,5)+ABS(Component/Substrate (position_no, 6)−2.5)))/2, where, forposition 1 and Freq. B in the table 922 of FIG. 9B, the absolute value“ABS”=(ABS(2.6−2.5+ABS(2.4−2.5)))/2=0.1; and so on.

In various embodiments, the control unit 321 c may compare the ABSvalues with those of neighboring positions. For instance, for position 3(third row of values in the table 922 of FIG. 9B), the control unit 321c may compare the ABS value in the third row with the ABS values in thesecond and fourth rows. In a case where the ABS value in the third rowis higher than each of the ABS values in the second and fourth rows, thecontrol unit 321 c may compare the ABS value in the third row with apredefined threshold, such as, but not limited to, a noise level. If theABS value in the third row satisfies (e.g., exceeds) the threshold, thecontrol unit 321 c may identify that ABS value as a candidate peak powervalue. In embodiments where a rotatable component/substrate is involved(e.g., the top substrate 630 t of the polarization shifter 630), thecomponent/substrate positions are configured rotationally, and thusrespective ABS values in “beginning” and “end” positions may be comparedwith those of rotational neighbor positions. For example, the ABS valueof position 1 (first row of values in the table 922 of FIG. 9B) may becompared with the ABS values in the sixteenth and second rows. Thecomparison may be performed until all of the ABS values have beencompared with those of neighboring positions, and all the candidate peakvalues are identified.

Once the candidate peak values have been identified for both Freq. A andFreq. B, in various embodiments, the control unit 321 c may identify theoptimal (or best) position for the component/substrate. Thisidentification may be performed based on comparisons of the candidatepeak ABS values for Freq. A and Freq. B. Some example comparisons foridentifying the optimal (or best) position are as follows:

If Freq. A and Freq B have the same candidate peak ABS value in a givenposition, such as, candidate peaks P_(A2), P_(A9), P_(A14), P_(B5), andP_(B9), then the control unit 321 c may identify position 9 as being theoptimal (or best) component/substrate position;

If Freq. A and Freq B have similar candidate peak ABS values (e.g.,within a threshold difference from one another), and if the candidatepeak values are: P_(A2), P_(A9), P_(A14), P_(B5), and P_(B10), then thecontrol unit 321 c may identify position 9 as being the optimal (orbest) component/substrate position in a case where P_(A9)>P_(B10), orthe control unit 321 c may identify position 10 as being the optimal (orbest) component/substrate position in a case where P_(A9)<P_(B10);

If Freq. A and Freq. B do not have similar candidate peak ABS values(e.g., they are not within the threshold difference from one another),and if the candidate peak values are: P_(A2), P_(A14), P_(B5), andP_(B9), then the control unit 321 c may identify a default position(e.g., position 1 or a current position of the column) as the optimal(or best) component/substrate position; and

If Freq. A and Freq. B have more than one qualifying position, then thecontrol unit 321 c may identify the position with the highest peak ABSvalue as the optimal (or best) component/substrate position.

Based on the identified optimal (or best) position, the control unit 321c may then control the motor 702 to move the component/substrate to thatposition to facilitate mitigation or avoidance of interference/PIM.

FIGS. 10A and 10B illustrate an example implementation for evaluatingpolarization shifting in accordance with various aspects describedherein. The implementation may include a commercial base station radiohaving dual band support, with 2 Tx/Rx configured for one of the bandsand 4 Tx/Rx for the other band. The radio may have a single(dual-polarized) radiating element in a 2-by-2 implementation and tworadiating elements in a 4-by-4 implementation. In evaluatingpolarization shifting, a PIM source (i.e., vertical steel wool bar) wasplaced across from the antenna(s) in a known position/orientation. Sincethe physical rotation of the antenna is equivalent to the rotation of asingle radiating element (in the 2-by-2 implementation), such physicalrotation was used to simulate or effect rotation of the radiatingelement. For each rotation, the reflected signal was captured andanalyzed with a base band unit and a PIM CPRI analyzer. The PIM levelprior to the rotation to an optimal (best) angle/position is compared tothe PIM level after such rotation. In order to precisely rotate theantenna by precise amounts, a mounting platform was constructed using apiece of plywood and two panoramic tripod heads. The tripod heads weredesigned to be used in panoramic photography applications, but work wellas a general-purposed rotator with 15-degree stops. Where the PIM sourceis in a known orientation (e.g., vertically oriented), rotation of theantenna such that a first sub-element of the radiating element isvertically oriented and a second sub-element of the radiating element ishorizontally oriented enables a “clean” signal to be picked up from thehorizontally oriented sub-element, thereby resulting in mitigation, oravoidance, of the PIM. FIGS. 10C and 10D show mitigation results fordifferent sources of PIM in accordance with various aspects describedherein. These results indicate that the techniques employed in variousembodiments described herein (in which orthogonal RF signal rotation isperformed to mimic physical rotation of radiating elements) are highlyeffective for PIM mitigation or avoidance.

To reiterate, PIM can seriously degrade UL performance in acommunications system, such as 4G/5G base stations. Transmissions in twoor more frequency bands by a base station or by multiple base stationscan lead to nonlinear mixing of DL carriers, resulting in anintermodulation product—i.e., PIM. PIM can be internal to a base stationand its antenna system or external thereto. Internal PIM may be causedby non-linearities in passive devices (e.g., filters, duplexers,connectors, cables, antenna components, etc.) within a transmit signalpath of a multi-band base station. The mixing of DL carriers within eachpath can result in internal PIM. That is, a given path may suffer frominternal PIM simply due to the mixing of DL carriers transmitted in thatpath. Internal PIM generated by the mixing of DL carriers transmitted indifferent paths is generally not a problem. External PIM may begenerated by an object that is external to a base station and itsantenna system—e.g., a non-linear metallic object in the vicinity of anantenna (typically within 10 feet), such as the PIM source 200 p of FIG.2A. DL carriers transmitted over different paths may illuminate anexternal PIM source and mix to generate PIM externally. Both multi-bandand single-band base stations are susceptible to external PIM. Considera base station operating over two carriers in different bands—e.g., DL 1and DL 2 (e.g., 1102 of FIG. 11A). For PIM to be generated by a PIMsource, both DL carriers must be received by the PIM source. If only oneof the DL carriers is received by the PIM source, no PIM will begenerated since there will be no intermodulation mixing. Thus, PIM canbe avoided if simultaneous reception of either DL 1 or DL 2 by the PIMsource is prevented.

In exemplary embodiments, PIM may be avoided or mitigated by modifyingor adjusting path/port mapping and/or the polarization of DL signals. Inparticular, DL swapping and DL swapping and rotationimplementations/algorithms are described herein that prevent or reducethe generation of internal or external PIM by altering DL path/portmapping, leveraging DL signal transmission timing differences, and/ormanipulating the polarization of one or more of multiple DLs such thatDL signals of different frequencies are not received simultaneously (orat the same strength) by a PIM source. While the description hereafterdescribes examples of DL swapping and DL swapping and rotation involvingtwo carriers, it is to be appreciated and understood that the DLswapping and DL swapping and rotation implementations may be applied incommunications systems that operate over three or more carriers. In anycase, by preventing the reception by the PIM source of one or more DLcarriers, the frequency of the intermodulation product may be altered,thereby avoiding or preventing PIM from being generated and impactingULs.

To illustrate the DL swapping and DL swapping and rotationimplementations, reference is made to MIMO systems in which multiplesignals, referred to as constituent signals, are transmitted over eachDL carrier. In a 2- or 4-port DL transmission system (2 Tx or 4 Tx), forinstance, 2- or 4-port dual-slant cross-polarized (Xpol) antennas may beused (e.g., FIGS. 3A and 11B). In the case of multi-band operation wheretwo carriers (one in each of two bands) DL 1 and DL 2 are eachconfigured to transmit four signals (4 Tx), and where a 4-port antenna(with two columns of dual-slant crossed dipoles) is employed fortransmitting over the two bands, we can have the following:

A, a, AA, aa represent constituent signals for band 1 (DL 1);

B, b, BB, bb represent constituent signals for band 2 (DL 2); and

p1, p2, p3, p4 represent the [+45, −45, +45, −45] ports of the Xpolantenna (e.g., from left to right) (1104 of FIG. 11A).

Typically, DL signals in such a configuration may be mapped (by default)to transmitter paths and antenna ports as follows:

path 1 to p1=A, B;

path 2 to p2=a, b;

path 3 to p3=AA, BB; and

path 4 to p4=aa, bb,

which can also be written as: [A a AA aa]=[p1 p2 p3 p4], [B b BB bb]=[p1p2 p3 p4], where path mapping may determine which signals aretransmitted via a +45 degree dipole polarization and which signals aretransmitted via a −45 degree dipole polarization. Here, the DL carriersmay be combined into a multi-carrier signal before they are convertedinto high power RF signals by signal path blocks. Such signal pathblocks may include power amplifiers, filters, duplexers, connectors,cabling to the antenna, etc. and, therefore, can introduce multiplesources of internal PIM. In particular, internal PIM may be generated inpath 1 from the mixing of A and B, may be generated in path 2 from themixing of a and b, and so on. Additionally, the default path and antennaport mapping may also play a role in external PIM generation.

In exemplary embodiments, mapping block(s)/functionality may be providedin DLs to change or alter path and antenna port mapping. The mapping maybe hardcoded or hardwired or may, alternatively, be implemented as acontrol system (e.g., in hardware, software, or a combination ofhardware and software) that selectively maps signals to paths/portsbased on detected PIM characteristics, such as the polarization of thePIM. Configuring how the constituent signals of each of the DL carriersare mapped to the paths and antenna ports can affect (or alter)how/whether PIM is generated. FIG. 11B is a block diagram 1110illustrating an example, non-limiting embodiment of path/port mappingfunctionality in a downlink signal path of a multi-band communicationssystem in accordance with various aspects described herein. As shown inFIG. 11B, a dual-band antenna 1112 may be communicatively coupled topaths 1, 2, 3, and 4 of a multi-band base station via ports p1, p2, p3,and p4. In various embodiments, the dual band antenna 1112 may besimilar to, may be the same as, or may otherwise correspond to theantenna 210 of FIG. 2A or the antenna 310 of FIG. 3A. For instance, theports p1, p2, p3, and p4 may variously correspond to the ports 314 h,314 i, 315 h, and 315 i of the antenna 310 of FIG. 3A. In certainembodiments, the multi-band base station of FIG. 11B may correspond to aradio—e.g., the radio 340 of FIG. 3A, a baseband unit (e.g., one or moredistributed units), or any other device or system of a radio accessnetwork (RAN). In the above-described default mapping, carrier combiningmay result in A+B feeding into path 1, a+b feeding in path 2, AA+BBfeeding into path 3, and aa+bb feeding into path 4. However, inclusionof mappers 1114 and 1116 into the base station as shown in FIG. 11Bpermits altered mapping of constituent signals to the paths/antennaports to affect (or alter) how/whether PIM is generated.

In certain embodiments, mapping block(s) or functionality may similarlybe employed in separate single-band base stations or transmitters, eachwith its own antenna system. FIG. 11C is a block diagram 1120illustrating an example, non-limiting embodiment of path/port mappingfunctionality in downlink signal paths of single-band communicationssystems (including antennas 1122 and 1124) in accordance with variousaspects described herein. While internal PIM might not be an issue heresince each of the signal path blocks is illuminated by a single carrier,external PIM is nevertheless a problem due to possible illumination ofan external PIM source by both carriers. The inclusion of mapping blocksas shown in FIG. 11C may enable mapping of constituent signals tospecific paths/antenna ports to affect (or alter) how/whether PIM isgenerated.

In exemplary embodiments, the timing of DL signal transmissions can beleveraged in conjunction with the aforementioned path and port mappingto mitigate or avoid PIM. In LTE, for instance, the DL cell specificreference signal (RS) is generally used to support demodulation at UEs.RS may be transmitted at different times on different antenna ports.FIG. 11D illustrates an example, non-limiting embodiment of a particularpath/port mapping in a downlink signal path of a multi-bandcommunications system in accordance with various aspects describedherein. The communications system 1140 shown may correspond to thesystem 1110 of FIG. 11B. Reference number 1130 of FIG. 11D illustratesRS timing for a 4 Tx mode. As shown, RS is transmitted in symbols 0 and4 via antenna ports 1 and 2 (i.e., early transmissions) and on symbols 1via antenna ports 3 and 4 (i.e., late transmissions). With reference tothe abovementioned constituent signal terminology, RS for DL 1 istransmitted early in A and a and late in AA and aa. Similarly, RS for DL2 is transmitted early in B and b and late in BB and bb. Here, addingthe letters e and/to these signal names to designate early/latetransition timing, and using default path and antenna port mapping,yields:

p1=Ae, Be;

p2=ae, be;

p3=AA1, BB1; and

p4=aa1, bb1.

If a PIM source, whether internal or external, receives the RS of DL 1and DL 2 at the same time, PIM may be generated from the mixing of theseRS. However, if the PIM source receives the RS from DL 1 and RS from DL2 at different times, PIM can be avoided. PIM that is generated from themixing of RS is referred to herein as RS PIM. While RS signals are notthe only DL signals that mix and generate PIM, the impact of RS PIM issignificant to the overall degradation of the UL because RS PIM canintroduce interference every 3 out of every 7 time slots, regardless ofthe amount of DL traffic or number of active users. Therefore, RS PIMcan impact the reception of every UL message that is received by a givenbase station.

Under the aforementioned default or standard path and port mapping, RSfrom DL 1 and DL 2 are transmitted at the same time on all paths. Thus,if there are internal PIM sources in any of the four signal paths, PIMwill be generated. Exemplary DL swapping embodiments address this issueand avoid generation of internal PIM due to RS by altering path mappingbased on the timing of RS signals for each of the ports—i.e. as follows(1140 of FIG. 11D):

p1=Ae, BB1;

p2=AA1, Be;

p3=ae, bb1; and

p4=aa1, be.

With this exemplary path mapping, the generation of RS PIM can beavoided altogether since RS from DL 1 and DL 2 are prevented from beingsimultaneously active in any of the paths. In this way, knowledge of RStiming can be used to map the DL constituent signals to particularpaths/ports to avoid generation of RS PIM.

It is to be appreciated and understood that the DL swappingimplementation/algorithm is not limited to mitigating intermodulationfrom passive sources. In various embodiments, DL swapping can beemployed to reduce intermodulation caused by active component(s),including, but not limited to, diodes, transistors, power amplifiers,and any other devices in the transmit signal path. It is also to beappreciated and understood that other path mapping schemes may beutilized to eliminate or reduce RS PIM generation.

To reiterate, external PIM sources are typically linearly polarized,meaning that the electric field generated by the source has a dominantorientation. For the PIM source to generate a significant amount of PIM,it needs to be a “good antenna”—i.e., capable of receiving the DLseffectively, mixing them, and then radiating the mixed signals. Dipole-and monopole-like structures, such as pipes, ducts, and roof flashingmounted in the vicinity of an antenna, make for good antennas, andtherefore, are good PIM sources. The electric field of PIM generated byany of these objects will be linearly polarized (a polarization thatmatches the orientation of the physical structure of the object). Thus,the amount of energy received by the PIM source from each of the DLsignals will depend on the relative polarization of the PIM source withrespect to the polarization of the DL signals. Consider a simple examplewhere an external PIM source, with a +45 degree polarization, is locatedin front of an antenna. Because of its orientation, the PIM source willpick up energy transmitted by the +45 dipole ports of the antenna. FIG.11E illustrates a dual-band antenna with default path/port mapping incomparison with altered path/port mapping in accordance with variousaspects described herein. With the aforementioned default path andantenna port mapping, the PIM source will be illuminated by the DLsignals Ae, AA1, Be, and BB1, and not by ae, aa1, be, or bb1 (1160 ofFIG. 11E). Since the PIM source is illuminated by two early and two latetransmissions, RS PIM will be generated. In exemplary embodiments of DLswapping, knowledge of RS timing can be used in conjunction with theknown polarizations of antenna ports to facilitate avoidance of RS PIM.In various embodiments, alteration of path/port mapping based on thetiming of RS signals and port polarization may be as follows:

p1 (+45)=Ae, BB1;

p2 (−45)=AA1, Be;

p3 (+45)=ae, bb1; and

p4 (−45)=aa1, be (1162 of FIG. 11E).

With this mapping, DL 1 may transmit early on the +45 degreepolarization and late on the −45 degree polarization. Similarly, DL 2may transmit late on the +45 degree polarization and early on the −45degree polarization. This results in the +45 degree polarized PIM sourcereceiving only early transmissions from DL 1 and late transmissions fromDL 2. Since RS is not received simultaneously by the PIM source, RS PIMmay therefore be avoided. This may be the case whether the PIM source isoriented at a +45 degree tilt or a −45 degree tilt.

In various embodiments, DL swapping may be adapted to address externalPIM sources oriented in other angles or polarizations (i.e., other thanat a +45 degree tilt or a −45 degree tilt). In exemplary embodiments, DLpolarization may be rotated to be orthogonal to the determinedorientation/polarization of an external PIM source. FIG. 11F is a blockdiagram 1170 illustrating an example, non-limiting embodiment ofpath/port mapping functionality (1114, 1116) employed in conjunctionwith polarization rotation functions (1172, 1174) in a downlink signalpath of a multi-band communications system in accordance with variousaspects described herein. The communications system 1170 shown maycorrespond to the system 1140 of FIG. 11D, but with the addition ofrotator functionality 1172, 1174. In various embodiments, thepolarization of DL 1 may be rotated by rotator 1172 such that early RSare aligned with the PIM source and late RS are perpendicular to the PIMsource, or vice versa. Additionally, or alternatively, the polarizationof DL 2 may be rotated by rotator 1174 such that late RS are alignedwith the PIM source and early RS are perpendicular to the PIM source, orvice versa. Polarization rotation may be performed by mixing the DLsignals destined for each of the crossed-dipoles. In certainembodiments, rotators 1172 and 1174 may each be implemented usingdigital signal processing techniques (e.g., based on the equations 202p/202 q/202 r of FIGS. 2B-2D or equivalents of equations 202 p/202 q/202r).

FIG. 11G illustrates a dual-band antenna with altered path/port mappingemployed with polarization rotation in accordance with various aspectsdescribed herein. As an illustration of DL swapping and rotation,consider a case where an external PIM source with a determined tilt of22 degrees is located in front of the antenna (e.g., 1180 of FIG. 11G).Here, DL signal constituents may be remapped, and the polarizations ofDL 1 and DL 2 may be rotated to match the 22 degree tilt of the PIMsource. By virtue of these manipulations, the PIM source may onlyreceive early RS from DL 1 and late RS from DL 2 (i.e., DLs at differenttimes), thereby avoiding generation of RS PIM. In this way, knowledge ofRS timing can be used in conjunction with known antenna portpolarizations and a determined PIM source polarization to (i) map the DLconstituent signals to particular paths/ports and/or (ii) rotate the DLpolarizations so as to facilitate avoidance generation of RS PIM.

It is to be appreciated and understood that rotation of thepolarizations of DL signals (1172, 1174, etc.) can be performed in anysuitable manner, such as in the RF domain (e.g., via the RPM 220 or 320)or via physical rotation of crossed-dipoles of an antenna.

It is also to be appreciated and understood that the quantities of basestations, DLs or carriers, constituent signals per DL, carriercombiners, paths, mappers, rotators, antennas, crossed-dipole pairs, PIMsources, etc. shown in one or more of FIGS. 11B-11D and 11F are merelyexemplary. That is, the systems shown in FIGS. 11B-11D and 11F mayinclude any quantities of (e.g., more or fewer) base stations, DLs orcarriers, constituent signals per DL, carrier combiners, paths, mapperblocks, rotators, antennas, crossed-dipole pairs, PIM sources, etc.

FIG. 12A depicts an illustrative embodiment of a method 1200 inaccordance with various aspects described herein. In some embodiments,one or more process blocks of FIG. 12A can be performed by a controlunit, such as the control unit 321 c. In some embodiments, one or moreprocess blocks of FIG. 12A may be performed by another device or a groupof devices separate from or including the control unit, such as themonitoring/detection unit(s) 321 d, the RPM 320, etc.

At 1202, the method can include causing a component/substrate of an RFmechanical device to incrementally occupy a plurality of positions. Forexample, the control unit 321 c can, similar to that described elsewhereherein, perform one or more operations that include causing acomponent/substrate of an RF mechanical device (e.g., the top substrate530 t of the polarization shifter 530 or the top substrate 630 t of thepolarization shifter 630) to incrementally occupy a plurality ofpositions. In various embodiments, the component/substrate may thus bemoved in increments such that the component/substrate incrementallyoccupies different linear/rotational positions in a continuous orsequential manner, where measurements from orthogonal RF input signalsmay be made at each of the incremental steps to identify the optimal (orbest) position for the component/substrate.

At 1204, the method can include obtaining, from a detection unit and foreach of the plurality of positions, measurements relating to orthogonalRF input signals. For example, the control unit 321 c can, similar tothat described elsewhere herein, perform one or more operations thatinclude obtaining, from a detection unit and for each of the pluralityof positions, measurements relating to orthogonal RF input signals.

At 1206, the method can include, based on the measurements, identifyingan optimal position of the component/substrate at which an impact ofpassive intermodulation (PIM) on a communications system is minimized.For example, the control unit 321 c can, similar to that describedelsewhere herein, perform one or more operations that include, based onthe measurements, identifying an optimal position of thecomponent/substrate at which an impact of passive intermodulation (PIM)on a communications system is minimized.

At 1208, the method can include causing the component/substrate tooccupy the optimal position to mitigate or avoid the PIM. For example,the control unit 321 c can, similar to that described elsewhere herein,perform one or more operations that include causing thecomponent/substrate to occupy the optimal position to mitigate or avoidthe PIM.

While for purposes of simplicity of explanation, the respectiveprocesses are shown and described as a series of blocks in FIG. 12A, itis to be understood and appreciated that the claimed subject matter isnot limited by the order of the blocks, as some blocks may occur indifferent orders and/or concurrently with other blocks from what isdepicted and described herein. Moreover, not all illustrated blocks maybe required to implement the methods described herein.

FIG. 12B depicts an illustrative embodiment of a method 1210 inaccordance with various aspects described herein. In some embodiments,one or more process blocks of FIG. 12B can be performed by an RFmechanical device.

At 1212, the method can include receiving, by an RF mechanical device,signals relating to one or more crossed-dipole radiating elements of anantenna system. For example, similar to that described elsewhere herein,an RF mechanical device may receive signals relating to one or morecrossed-dipole radiating elements of an antenna system.

At 1214, the method can include performing, by the RF mechanical device,polarization adjusting of the signals to derive output signals havingpolarizations that are adjusted in a manner that mimics physicalrotation of the one or more crossed-dipole radiating elements. Forexample, similar to that described elsewhere herein, the RF mechanicaldevice may perform polarization adjusting of the signals to deriveoutput signals having polarizations that are adjusted in a manner thatmimics physical rotation of the one or more crossed-dipole radiatingelements.

At 1216, the method can include providing, by the RF mechanical device,the output signals to enable avoidance of interference or PIM. Forexample, similar to that described elsewhere herein, the RF mechanicaldevice may provide the output signals to enable avoidance ofinterference or PIM.

While for purposes of simplicity of explanation, the respectiveprocesses are shown and described as a series of blocks in FIG. 12B, itis to be understood and appreciated that the claimed subject matter isnot limited by the order of the blocks, as some blocks may occur indifferent orders and/or concurrently with other blocks from what isdepicted and described herein. Moreover, not all illustrated blocks maybe required to implement the methods described herein.

FIG. 12C depicts an illustrative embodiment of a method 1220 inaccordance with various aspects described herein. In some embodiments,one or more process blocks of FIG. 12C can be performed by a doubletrombone shifter device, such as the double trombone shifter device 530.

At 1222, the method can include receiving, by a double trombone shifterdevice, signals relating to one or more crossed-dipole radiatingelements of an antenna system. For example, similar to that describedelsewhere herein, the double trombone shifter device 530 may receivesignals relating to one or more crossed-dipole radiating elements of anantenna system.

At 1224, the method can include performing, by the double tromboneshifter device, polarization adjusting of the signals to derive outputsignals having polarizations that are adjusted in a manner that mimicsphysical rotation of the one or more crossed-dipole radiating elements.For example, similar to that described elsewhere herein, the doubletrombone shifter device 530 may perform polarization adjusting of thesignals to derive output signals having polarizations that are adjustedin a manner that mimics physical rotation of the one or morecrossed-dipole radiating elements.

At 1226, the method can include providing, by the double tromboneshifter device, the output signals to enable avoidance of interferenceor PIM. For example, similar to that described elsewhere herein, thedouble trombone shifter device 530 may provide the output signals toenable avoidance of interference or PIM.

While for purposes of simplicity of explanation, the respectiveprocesses are shown and described as a series of blocks in FIG. 12C, itis to be understood and appreciated that the claimed subject matter isnot limited by the order of the blocks, as some blocks may occur indifferent orders and/or concurrently with other blocks from what isdepicted and described herein. Moreover, not all illustrated blocks maybe required to implement the methods described herein.

FIG. 12D depicts an illustrative embodiment of a method 1230 inaccordance with various aspects described herein. In some embodiments,one or more process blocks of FIG. 12D can be performed by a radio 340of FIG. 3A, a baseband unit (e.g., one or more distributed units), orany other device or system of a radio access network (RAN).

At 1232, the method can include obtaining data regarding interference orpassive intermodulation (PIM) originating from one or more interferencesources. For example, similar to that described elsewhere herein, dataregarding interference or passive intermodulation (PIM) originating fromone or more interference sources may be obtained.

At 1234, the method can include electronically adjusting polarizationsof signals relating to radiating elements of an antenna system, theelectronically adjusting being performed for multiple frequency bandsand facilitating mitigation of the interference or the PIM. For example,similar to that described elsewhere herein, polarizations of signalsrelating to radiating elements of an antenna system may beelectronically adjusted, the electronically adjusting being performedfor multiple frequency bands and facilitating mitigation of theinterference or the PIM.

While for purposes of simplicity of explanation, the respectiveprocesses are shown and described as a series of blocks in FIG. 12D, itis to be understood and appreciated that the claimed subject matter isnot limited by the order of the blocks, as some blocks may occur indifferent orders and/or concurrently with other blocks from what isdepicted and described herein. Moreover, not all illustrated blocks maybe required to implement the methods described herein.

In various embodiments, a polarization rotation system may include aradio frequency (RF) mechanical device, and a plurality of reciprocalports for the RF mechanical device, the plurality of reciprocal portsincluding a first pair of reciprocal ports as inputs for the RFmechanical device, and a second pair of reciprocal ports as outputs forthe RF mechanical device, the RF mechanical device being configured toperform polarization rotation of signals to enable avoidance ofinterference.

In some implementations of these embodiments, the polarization rotationis performed in an RF domain, the interference comprises passiveintermodulation (PIM), and the signals comprise input signals and outputsignals of the RF mechanical device.

In some implementations of these embodiments, the first pair ofreciprocal ports interfaces with crossed-dipole radiating elements of anantenna system, and the second pair of reciprocal ports interfaces witha remote radio unit (RRU) or a remote radio head (RRH).

In some implementations of these embodiments, the RF mechanical deviceis configured to perform the polarization rotation for transmit (Tx)signals, receive (Rx) signals, or both, and the polarization rotationmimics physical rotation of crossed-dipole radiating elements of anantenna system.

In some implementations of these embodiments, the polarization rotationfurther comprises an additional RF mechanical device, and a set ofreciprocal ports for the additional RF mechanical device, the set ofreciprocal ports including reciprocal ports as inputs for the additionalRF mechanical device, and reciprocal ports as outputs for the additionalRF mechanical device, the additional RF mechanical device beingconfigured to perform polarization rotation of signals to enableavoidance of interference.

In some implementations of these embodiments, the polarization rotationsystem is implemented in an antenna system, in a radio, or in astandalone system that interfaces the antenna system and the radio.

In various embodiments, a method may include receiving, by a radiofrequency (RF) mechanical device, signals relating to one or morecrossed-dipole radiating elements of an antenna system, performing, bythe RF mechanical device, polarization rotation of the signals to deriveoutput signals having polarizations that are rotated in a manner thatmimics physical rotation of the one or more crossed-dipole radiatingelements, and providing, by the RF mechanical device, the output signalsto enable avoidance of interference.

In some implementations of these embodiments, the polarization rotationis performed in an RF domain, and the interference comprises passiveintermodulation (PIM).

In some implementations of these embodiments, the providing comprisesproviding the output signals to a remote radio unit (RRU) or a remoteradio head (RRH).

In some implementations of these embodiments, the RF mechanical deviceis configured to perform the polarization rotation for transmit (Tx)signals, receive (Rx) signals, or both.

In some implementations of these embodiments, the RF mechanical deviceis implemented in the antenna system, in a radio, or in a standalonesystem that interfaces the antenna system and the radio.

In some implementations of these embodiments, each crossed-dipoleradiating element of the one or more crossed-dipole radiating elementsoperates in multiple frequency bands.

In some implementations of these embodiments, the RF mechanical devicehas a symmetrical configuration.

In various embodiments, a communications system may include an antennahaving multiple arrays of orthogonally-polarized radiating elements, anda device arranged to communicatively couple with one or more arrays ofthe multiple arrays of orthogonally-polarized radiating elements, thedevice being configured to perform polarization rotation of signalsrelating to the one or more arrays, the polarization rotation mimickingphysical rotation of the one or more arrays and enabling mitigation ofinterference.

In some implementations of these embodiments, the polarization rotationis performed in a radio frequency (RF) domain, and the interferencecomprises passive intermodulation (PIM).

In some implementations of these embodiments, the device is configuredto perform the polarization rotation for transmit (Tx) signals, receive(Rx) signals, or both, and the signals comprise input signals and outputsignals of the device.

In some implementations of these embodiments, the polarization rotationis integrated in the antenna.

In some implementations of these embodiments, the polarization rotationis integrated in a remote radio unit (RRU) or a remote radio head (RRH).

In some implementations of these embodiments, the polarization rotationis at least partially performed using a motor, a drive assembly, or acombination thereof.

In some implementations of these embodiments, the device comprises oneor more waveguides, one or more cavities, or combinations thereof.

In various embodiments, an apparatus may include a pair of hybridcouplers, and a dual shifter, the dual shifter being mechanicallyadjustable to effect polarization rotation of signals relating to adual-polarized pair of crossed-dipole elements, the polarizationrotation mimicking physical rotation of the dual-polarized pair ofcrossed-dipole elements and enabling avoidance of interference.

In some implementations of these embodiments, the polarization rotationis performed in a radio frequency (RF) domain, and the interferencecomprises passive intermodulation (PIM).

In some implementations of these embodiments, the apparatus may furthercomprise a lower substrate having disposed thereon a first pair oftransmission lines, and an upper substrate having disposed thereon asecond pair of transmission lines, wherein the first and second pairs oftransmission lines form at least a portion of the dual shifter.

In some implementations of these embodiments, the pair of hybridcouplers and the dual shifter are arranged in a symmetricalconfiguration.

In some implementations of these embodiments, the dual shifter comprisesa double trombone shifter that is mechanically adjustable in a linearmanner or a dual overlapping arch shifter that is mechanicallyadjustable in a rotational manner.

In some implementations of these embodiments, the apparatus may furthercomprise a motor and a drive assembly configured to mechanically adjustthe dual shifter to effect the polarization rotation.

In various embodiments, a polarization rotator may include a lowersubstrate having disposed thereon first and second hybrid couplers, afirst transmission line coupled to the first hybrid coupler, and asecond transmission line coupled to the second hybrid coupler. Thepolarization rotator may further include an upper substrate adjacent tothe lower substrate and having disposed thereon third and fourthtransmission lines, the third transmission line at least partiallyoverlapping the first and second transmission lines to form a firstcoupled line, the fourth transmission line at least partiallyoverlapping the first and second transmission lines to form a secondcoupled line, the upper substrate being displaceable relative to thelower substrate to effect polarization rotation of orthogonal signalsinputted to the first hybrid coupler, and to provide polarizationrotated signals at outputs of the second hybrid coupler to facilitateavoidance of interference.

In some implementations of these embodiments, displacement of the uppersubstrate relative to the lower substrate provides a double simultaneousphase shifting effect that results in the polarization rotation.

In some implementations of these embodiments, arrangement of the first,second, third, and fourth transmission lines form a double tromboneshifter.

In some implementations of these embodiments, either or both of thefirst hybrid coupler and the second hybrid coupler comprises a 180degree hybrid coupler.

In some implementations of these embodiments, each of the first hybridcoupler and the second hybrid coupler comprises a 90 degree hybridcoupler.

In some implementations of these embodiments, the polarization rotatormay further comprise a motor and a drive assembly coupled to the uppersubstrate.

In some implementations of these embodiments, the polarization rotatoris implemented in an antenna, in a radio, or in a standalone device thatinterfaces the antenna and the radio, and the interference comprisespassive intermodulation (PIM).

In various embodiments, a method may include receiving, by a doubletrombone shifter device, signals relating to one or more crossed-dipoleradiating elements of an antenna system, performing, by the doubletrombone shifter device, polarization rotation of the signals to deriveoutput signals having polarizations that are rotated in a manner thatresults in a virtual physical rotation of the one or more crossed-dipoleradiating elements, and providing, by the double trombone shifterdevice, the output signals to enable avoidance of interference.

In some implementations of these embodiments, the double tromboneshifter device has a symmetrical configuration.

In some implementations of these embodiments, the double tromboneshifter device comprises a pair of 90 degree hybrid couplers.

In some implementations of these embodiments, the polarization rotationis performed in a radio frequency (RF) domain.

In some implementations of these embodiments, the performing thepolarization rotation involves use of a motor and a drive assembly.

In some implementations of these embodiments, the providing the outputsignals comprises providing the output signals to a radio.

In some implementations of these embodiments, the double tromboneshifter device is implemented in the antenna system, in a radio, or in astandalone device that interfaces the antenna system and the radio, andthe interference comprises passive intermodulation (PIM).

In various embodiments, a method may include obtaining data regardinginterference originating from one or more interference sources, andelectronically rotating polarizations of signals relating tocrossed-dipole radiating elements of an antenna system, the antennasystem operating in multiple frequency bands, the electronicallyrotating being performed for a select number of frequency bands of themultiple frequency bands and facilitating mitigation of theinterference.

In some implementations of these embodiments, the electronicallyrotating is performed for transmit (Tx) signals, receive (Rx) signals,or both.

In some implementations of these embodiments, the electronicallyrotating is performed in a same or a different manner for transmit (Tx)signals and receive (Rx) signals.

In some implementations of these embodiments, the electronicallyrotating for the select number of frequency bands is performed in a sameor a different manner for signals in different bands of the multiplefrequency bands.

In some implementations of these embodiments, the signals compriseconstituent signals of downlink (DL) carriers, the method furthercomprising altering a mapping of the constituent signals to DL paths andports of the antenna system, the altering the mapping and theelectronically rotating being based on timing associated with theconstituent signals, polarizations of the ports of the antenna system,polarization of a passive intermodulation (PIM) source, or a combinationthereof.

In some implementations of these embodiments, the electronicallyrotating is performed in a remote radio unit (RRU), a remote radio head(RRH), a Common Public Radio Interface (CPRI) device, a baseband unit,or another device in a radio access network (RAN), and the interferencecomprises passive intermodulation (PIM).

In various embodiments, an apparatus may include a processing systemassociated with an antenna system and configured to perform operations,comprising receiving data regarding interference, and electronicallymanipulating, in a radio frequency (RF) domain, signals to rotatepolarizations thereof to facilitate mitigation or avoidance of theinterference, the signals relating to crossed-dipole radiating elementsof the antenna system, the antenna system operating in multiplefrequency bands, the electronically manipulating being performed for atleast two frequency bands of the multiple frequency bands.

In some implementations of these embodiments, the electronicallymanipulating is performed for transmit (Tx) signals, receive (Rx)signals, or both.

In some implementations of these embodiments, the apparatus isimplemented in a remote radio unit (RRU), a remote radio head (RRH), ora baseband unit.

In some implementations of these embodiments, the apparatus isimplemented in a Common Public Radio Interface (CPRI) device.

In some implementations of these embodiments, the electronicallymanipulating is performed without requiring any physical rotation of thecrossed-dipole radiating elements or a housing of the antenna system.

In some implementations of these embodiments, the signals includeorthogonal RF signals, and the electronically manipulating involvesprojection of the orthogonal RF signals in a different set of axes.

In some implementations of these embodiments, the interference comprisespassive intermodulation (PIM), and the electronically manipulating forthe at least two frequency bands is performed in a same or a differentmanner.

In various embodiments, a device may include a processing systemconfigured to detect interference originating from one or moreinterference sources, and perform virtual rotation of crossed-dipoleradiating elements of an antenna system by rotating, in a radiofrequency (RF) domain, polarizations of signals relating to thecrossed-dipole radiating elements, the antenna system operating inmultiple frequency bands, the rotating the polarizations being performedfor a select number of frequency bands of the multiple frequency bandsand facilitating mitigation of the interference.

In some implementations of these embodiments, the signals includeorthogonal RF signals, and the rotating the polarizations involvesprojection of the orthogonal RF signals in a different set of axes.

In some implementations of these embodiments, the rotating thepolarizations is performed for transmit (Tx) signals, receive (Rx)signals, or both.

In some implementations of these embodiments, the rotating thepolarizations is performed without requiring any movement of thecrossed-dipole radiating elements or a housing of the antenna system.

In some implementations of these embodiments, the device is implementedin a remote radio unit (RRU), a remote radio head (RRH), or a basebandunit.

In some implementations of these embodiments, the device is implementedin a Common Public Radio Interface (CPRI) system.

In some implementations of these embodiments, the rotating thepolarizations for the select number of frequency bands is performed in asame or a different manner for signals in different bands of themultiple frequency bands, and the interference comprises passiveintermodulation (PIM).

Turning now to FIG. 13, there is illustrated a block diagram of acomputing environment in accordance with various aspects describedherein. In order to provide additional context for various embodimentsof the embodiments described herein, FIG. 13 and the followingdiscussion are intended to provide a brief, general description of asuitable computing environment 1300 in which the various embodiments ofthe subject disclosure can be implemented. In particular, computingenvironment 1300 can be used in the implementation of network elements150, 152, 154, 156, access terminal 112, base station or access point122, switching device 132, media terminal 142, one or more (or acombination) of the control and monitoring/detection units describedabove with respect to FIGS. 3A-3C, component(s) of one or more of thesystems of FIGS. 11B-11D and 11F, etc. Each of these devices can beimplemented via computer-executable instructions that can run on one ormore computers, and/or in combination with other program modules and/oras a combination of hardware and software. For example, computingenvironment 1300 can facilitate, in whole or in part, detection ofinterference/PIM in a communications system and performing of action(s)relating to polarization shifting to enable mitigation or avoidance ofthe interference/PIM.

Generally, program modules comprise routines, programs, components, datastructures, etc., that perform particular tasks or implement particularabstract data types. Moreover, those skilled in the art will appreciatethat the methods can be practiced with other computer systemconfigurations, comprising single-processor or multiprocessor computersystems, minicomputers, mainframe computers, as well as personalcomputers, hand-held computing devices, microprocessor-based orprogrammable consumer electronics, and the like, each of which can beoperatively coupled to one or more associated devices.

As used herein, a processing circuit includes one or more processors aswell as other application specific circuits such as an applicationspecific integrated circuit, digital logic circuit, state machine,programmable gate array or other circuit that processes input signals ordata and that produces output signals or data in response thereto. Itshould be noted that while any functions and features described hereinin association with the operation of a processor could likewise beperformed by a processing circuit.

The illustrated embodiments of the embodiments herein can be alsopracticed in distributed computing environments where certain tasks areperformed by remote processing devices that are linked through acommunications network. In a distributed computing environment, programmodules can be located in both local and remote memory storage devices.

Computing devices typically comprise a variety of media, which cancomprise computer-readable storage media and/or communications media,which two terms are used herein differently from one another as follows.Computer-readable storage media can be any available storage media thatcan be accessed by the computer and comprises both volatile andnonvolatile media, removable and non-removable media. By way of example,and not limitation, computer-readable storage media can be implementedin connection with any method or technology for storage of informationsuch as computer-readable instructions, program modules, structured dataor unstructured data.

Computer-readable storage media can comprise, but are not limited to,random access memory (RAM), read only memory (ROM), electricallyerasable programmable read only memory (EEPROM), flash memory or othermemory technology, compact disk read only memory (CD-ROM), digitalversatile disk (DVD) or other optical disk storage, magnetic cassettes,magnetic tape, magnetic disk storage or other magnetic storage devicesor other tangible and/or non-transitory media which can be used to storedesired information. In this regard, the terms “tangible” or“non-transitory” herein as applied to storage, memory orcomputer-readable media, are to be understood to exclude onlypropagating transitory signals per se as modifiers and do not relinquishrights to all standard storage, memory or computer-readable media thatare not only propagating transitory signals per se.

Computer-readable storage media can be accessed by one or more local orremote computing devices, e.g., via access requests, queries or otherdata retrieval protocols, for a variety of operations with respect tothe information stored by the medium.

Communications media typically embody computer-readable instructions,data structures, program modules or other structured or unstructureddata in a data signal such as a modulated data signal, e.g., a carrierwave or other transport mechanism, and comprises any informationdelivery or transport media. The term “modulated data signal” or signalsrefers to a signal that has one or more of its characteristics set orchanged in such a manner as to encode information in one or moresignals. By way of example, and not limitation, communication mediacomprise wired media, such as a wired network or direct-wiredconnection, and wireless media such as acoustic, RF, infrared and otherwireless media.

With reference again to FIG. 13, the example environment can comprise acomputer 1302, the computer 1302 comprising a processing unit 1304, asystem memory 1306 and a system bus 1308. The system bus 1308 couplessystem components including, but not limited to, the system memory 1306to the processing unit 1304. The processing unit 1304 can be any ofvarious commercially available processors. Dual microprocessors andother multiprocessor architectures can also be employed as theprocessing unit 1304.

The system bus 1308 can be any of several types of bus structure thatcan further interconnect to a memory bus (with or without a memorycontroller), a peripheral bus, and a local bus using any of a variety ofcommercially available bus architectures. The system memory 1306comprises ROM 1310 and RAM 1312. A basic input/output system (BIOS) canbe stored in a non-volatile memory such as ROM, erasable programmableread only memory (EPROM), EEPROM, which BIOS contains the basic routinesthat help to transfer information between elements within the computer1302, such as during startup. The RAM 1312 can also comprise ahigh-speed RAM such as static RAM for caching data.

The computer 1302 further comprises an internal hard disk drive (HDD)1314 (e.g., EIDE, SATA), which internal HDD 1314 can also be configuredfor external use in a suitable chassis (not shown), a magnetic floppydisk drive (FDD) 1316, (e.g., to read from or write to a removablediskette 1318) and an optical disk drive 1320, (e.g., reading a CD-ROMdisk 1322 or, to read from or write to other high capacity optical mediasuch as the DVD). The HDD 1314, magnetic FDD 1316 and optical disk drive1320 can be connected to the system bus 1308 by a hard disk driveinterface 1324, a magnetic disk drive interface 1326 and an opticaldrive interface 1328, respectively. The hard disk drive interface 1324for external drive implementations comprises at least one or both ofUniversal Serial Bus (USB) and Institute of Electrical and ElectronicsEngineers (IEEE) 1394 interface technologies. Other external driveconnection technologies are within contemplation of the embodimentsdescribed herein.

The drives and their associated computer-readable storage media providenonvolatile storage of data, data structures, computer-executableinstructions, and so forth. For the computer 1302, the drives andstorage media accommodate the storage of any data in a suitable digitalformat. Although the description of computer-readable storage mediaabove refers to a hard disk drive (HDD), a removable magnetic diskette,and a removable optical media such as a CD or DVD, it should beappreciated by those skilled in the art that other types of storagemedia which are readable by a computer, such as zip drives, magneticcassettes, flash memory cards, cartridges, and the like, can also beused in the example operating environment, and further, that any suchstorage media can contain computer-executable instructions forperforming the methods described herein.

A number of program modules can be stored in the drives and RAM 1312,comprising an operating system 1330, one or more application programs1332, other program modules 1334 and program data 1336. All or portionsof the operating system, applications, modules, and/or data can also becached in the RAM 1312. The systems and methods described herein can beimplemented utilizing various commercially available operating systemsor combinations of operating systems.

A user can enter commands and information into the computer 1302 throughone or more wired/wireless input devices, e.g., a keyboard 1338 and apointing device, such as a mouse 1340. Other input devices (not shown)can comprise a microphone, an infrared (IR) remote control, a joystick,a game pad, a stylus pen, touch screen or the like. These and otherinput devices are often connected to the processing unit 1304 through aninput device interface 1342 that can be coupled to the system bus 1308,but can be connected by other interfaces, such as a parallel port, anIEEE 1394 serial port, a game port, a universal serial bus (USB) port,an IR interface, etc.

A monitor 1344 or other type of display device can be also connected tothe system bus 1308 via an interface, such as a video adapter 1346. Itwill also be appreciated that in alternative embodiments, a monitor 1344can also be any display device (e.g., another computer having a display,a smart phone, a tablet computer, etc.) for receiving displayinformation associated with computer 1302 via any communication means,including via the Internet and cloud-based networks. In addition to themonitor 1344, a computer typically comprises other peripheral outputdevices (not shown), such as speakers, printers, etc.

The computer 1302 can operate in a networked environment using logicalconnections via wired and/or wireless communications to one or moreremote computers, such as a remote computer(s) 1348. The remotecomputer(s) 1348 can be a workstation, a server computer, a router, apersonal computer, portable computer, microprocessor-based entertainmentappliance, a peer device or other common network node, and typicallycomprises many or all of the elements described relative to the computer1302, although, for purposes of brevity, only a remote memory/storagedevice 1350 is illustrated. The logical connections depicted comprisewired/wireless connectivity to a local area network (LAN) 1352 and/orlarger networks, e.g., a wide area network (WAN) 1354. Such LAN and WANnetworking environments are commonplace in offices and companies, andfacilitate enterprise-wide computer networks, such as intranets, all ofwhich can connect to a global communications network, e.g., theInternet.

When used in a LAN networking environment, the computer 1302 can beconnected to the LAN 1352 through a wired and/or wireless communicationsnetwork interface or adapter 1356. The adapter 1356 can facilitate wiredor wireless communication to the LAN 1352, which can also comprise awireless AP disposed thereon for communicating with the adapter 1356.

When used in a WAN networking environment, the computer 1302 cancomprise a modem 1358 or can be connected to a communications server onthe WAN 1354 or has other means for establishing communications over theWAN 1354, such as by way of the Internet. The modem 1358, which can beinternal or external and a wired or wireless device, can be connected tothe system bus 1308 via the input device interface 1342. In a networkedenvironment, program modules depicted relative to the computer 1302 orportions thereof, can be stored in the remote memory/storage device1350. It will be appreciated that the network connections shown areexample and other means of establishing a communications link betweenthe computers can be used.

The computer 1302 can be operable to communicate with any wirelessdevices or entities operatively disposed in wireless communication,e.g., a printer, scanner, desktop and/or portable computer, portabledata assistant, communications satellite, any piece of equipment orlocation associated with a wirelessly detectable tag (e.g., a kiosk,news stand, restroom), and telephone. This can comprise WirelessFidelity (Wi-Fi) and BLUETOOTH® wireless technologies. Thus, thecommunication can be a predefined structure as with a conventionalnetwork or simply an ad hoc communication between at least two devices.

Wi-Fi can allow connection to the Internet from a couch at home, a bedin a hotel room or a conference room at work, without wires. Wi-Fi is awireless technology similar to that used in a cell phone that enablessuch devices, e.g., computers, to send and receive data indoors and out;anywhere within the range of a base station. Wi-Fi networks use radiotechnologies called IEEE 802.11 (a, b, g, n, ac, ag, etc.) to providesecure, reliable, fast wireless connectivity. A Wi-Fi network can beused to connect computers to each other, to the Internet, and to wirednetworks (which can use IEEE 802.3 or Ethernet). Wi-Fi networks operatein the unlicensed 2.4 and 5 GHz radio bands for example or with productsthat contain both bands (dual band), so the networks can providereal-world performance similar to the basic 10BaseT wired Ethernetnetworks used in many offices.

The terms “first,” “second,” “third,” and so forth, which may be used inthe claims, unless otherwise clear by context, is for clarity only anddoesn't otherwise indicate or imply any order in time. For instance, “afirst determination,” “a second determination,” and “a thirddetermination,” does not indicate or imply that the first determinationis to be made before the second determination, or vice versa, etc.

In the subject specification, terms such as “store,” “storage,” “datastore,” data storage,” “database,” and substantially any otherinformation storage component relevant to operation and functionality ofa component, refer to “memory components,” or entities embodied in a“memory” or components comprising the memory. It will be appreciatedthat the memory components described herein can be either volatilememory or nonvolatile memory, or can comprise both volatile andnonvolatile memory, by way of illustration, and not limitation, volatilememory, non-volatile memory, disk storage, and memory storage. Further,nonvolatile memory can be included in read only memory (ROM),programmable ROM (PROM), electrically programmable ROM (EPROM),electrically erasable ROM (EEPROM), or flash memory. Volatile memory cancomprise random access memory (RAM), which acts as external cachememory. By way of illustration and not limitation, RAM is available inmany forms such as synchronous RAM (SRAM), dynamic RAM (DRAM),synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhancedSDRAM (ESDRAM), Synchlink DRAM (SLDRAM), and direct Rambus RAM (DRRAM).Additionally, the disclosed memory components of systems or methodsherein are intended to comprise, without being limited to comprising,these and any other suitable types of memory.

Moreover, it will be noted that the disclosed subject matter can bepracticed with other computer system configurations, comprisingsingle-processor or multiprocessor computer systems, mini-computingdevices, mainframe computers, as well as personal computers, hand-heldcomputing devices (e.g., PDA, phone, smartphone, watch, tabletcomputers, netbook computers, etc.), microprocessor-based orprogrammable consumer or industrial electronics, and the like. Theillustrated aspects can also be practiced in distributed computingenvironments where tasks are performed by remote processing devices thatare linked through a communications network; however, some if not allaspects of the subject disclosure can be practiced on stand-alonecomputers. In a distributed computing environment, program modules canbe located in both local and remote memory storage devices.

Some of the embodiments described herein can also employ artificialintelligence (AI) to facilitate automating one or more featuresdescribed herein. One or more embodiments can employ various AI-basedschemes for carrying out various embodiments thereof. Moreover, aclassifier can be employed. A classifier is a function that maps aninput attribute vector, x=(x1, x2, x3, x4, . . . , xn), to a confidencethat the input belongs to a class, that is, f(x)=confidence (class).Such classification can employ a probabilistic and/or statistical-basedanalysis (e.g., factoring into the analysis utilities and costs) todetermine or infer an action that a user desires to be automaticallyperformed. A support vector machine (SVM) is an example of a classifierthat can be employed. The SVM operates by finding a hypersurface in thespace of possible inputs, which the hypersurface attempts to split thetriggering criteria from the non-triggering events. Intuitively, thismakes the classification correct for testing data that is near, but notidentical to, training data. Other directed and undirected modelclassification approaches comprise, e.g., naïve Bayes, Bayesiannetworks, decision trees, neural networks, fuzzy logic models, andprobabilistic classification models providing different patterns ofindependence. Classification as used herein also is inclusive ofstatistical regression that is utilized to develop models of priority.

As will be readily appreciated, one or more of the embodiments canemploy classifiers that are explicitly trained (e.g., via a generictraining data) as well as implicitly trained (e.g., via observing UEbehavior, operator preferences, historical information, receivingextrinsic information). For example, SVMs can be configured via alearning or training phase within a classifier constructor and featureselection module. Thus, the classifier(s) can be used to automaticallylearn and perform a number of functions, including but not limited todetermining according to predetermined criteria which of the acquiredcell sites will benefit a maximum number of subscribers and/or which ofthe acquired cell sites will add minimum value to the existingcommunications network coverage, etc.

As used in some contexts in this application, in some embodiments, theterms “component,” “system” and the like are intended to refer to, orcomprise, a computer-related entity or an entity related to anoperational apparatus with one or more specific functionalities, whereinthe entity can be either hardware, a combination of hardware andsoftware, software, or software in execution. As an example, a componentmay be, but is not limited to being, a process running on a processor, aprocessor, an object, an executable, a thread of execution,computer-executable instructions, a program, and/or a computer. By wayof illustration and not limitation, both an application running on aserver and the server can be a component. One or more components mayreside within a process and/or thread of execution and a component maybe localized on one computer and/or distributed between two or morecomputers. In addition, these components can execute from variouscomputer readable media having various data structures stored thereon.The components may communicate via local and/or remote processes such asin accordance with a signal having one or more data packets (e.g., datafrom one component interacting with another component in a local system,distributed system, and/or across a network such as the Internet withother systems via the signal). As another example, a component can be anapparatus with specific functionality provided by mechanical partsoperated by electric or electronic circuitry, which is operated by asoftware or firmware application executed by a processor, wherein theprocessor can be internal or external to the apparatus and executes atleast a part of the software or firmware application. As yet anotherexample, a component can be an apparatus that provides specificfunctionality through electronic components without mechanical parts,the electronic components can comprise a processor therein to executesoftware or firmware that confers at least in part the functionality ofthe electronic components. While various components have beenillustrated as separate components, it will be appreciated that multiplecomponents can be implemented as a single component, or a singlecomponent can be implemented as multiple components, without departingfrom example embodiments.

Further, the various embodiments can be implemented as a method,apparatus or article of manufacture using standard programming and/orengineering techniques to produce software, firmware, hardware or anycombination thereof to control a computer to implement the disclosedsubject matter. The term “article of manufacture” as used herein isintended to encompass a computer program accessible from anycomputer-readable device or computer-readable storage/communicationsmedia. For example, computer readable storage media can include, but arenot limited to, magnetic storage devices (e.g., hard disk, floppy disk,magnetic strips), optical disks (e.g., compact disk (CD), digitalversatile disk (DVD)), smart cards, and flash memory devices (e.g.,card, stick, key drive). Of course, those skilled in the art willrecognize many modifications can be made to this configuration withoutdeparting from the scope or spirit of the various embodiments.

In addition, the words “example” and “exemplary” are used herein to meanserving as an instance or illustration. Any embodiment or designdescribed herein as “example” or “exemplary” is not necessarily to beconstrued as preferred or advantageous over other embodiments ordesigns. Rather, use of the word example or exemplary is intended topresent concepts in a concrete fashion. As used in this application, theterm “or” is intended to mean an inclusive “or” rather than an exclusive“or”. That is, unless specified otherwise or clear from context, “Xemploys A or B” is intended to mean any of the natural inclusivepermutations. That is, if X employs A; X employs B; or X employs both Aand B, then “X employs A or B” is satisfied under any of the foregoinginstances. In addition, the articles “a” and “an” as used in thisapplication and the appended claims should generally be construed tomean “one or more” unless specified otherwise or clear from context tobe directed to a singular form.

Moreover, terms such as “user equipment,” “mobile station,” “mobile,”subscriber station,” “access terminal,” “terminal,” “handset,” “mobiledevice” (and/or terms representing similar terminology) can refer to awireless device utilized by a subscriber or user of a wirelesscommunication service to receive or convey data, control, voice, video,sound, gaming or substantially any data-stream or signaling-stream. Theforegoing terms are utilized interchangeably herein and with referenceto the related drawings.

Furthermore, the terms “user,” “subscriber,” “customer,” “consumer” andthe like are employed interchangeably throughout, unless contextwarrants particular distinctions among the terms. It should beappreciated that such terms can refer to human entities or automatedcomponents supported through artificial intelligence (e.g., a capacityto make inference based, at least, on complex mathematical formalisms),which can provide simulated vision, sound recognition and so forth.

As employed herein, the term “processor” can refer to substantially anycomputing processing unit or device comprising, but not limited tocomprising, single-core processors; single-processors with softwaremultithread execution capability; multi-core processors; multi-coreprocessors with software multithread execution capability; multi-coreprocessors with hardware multithread technology; parallel platforms; andparallel platforms with distributed shared memory. Additionally, aprocessor can refer to an integrated circuit, an application specificintegrated circuit (ASIC), a digital signal processor (DSP), a fieldprogrammable gate array (FPGA), a programmable logic controller (PLC), acomplex programmable logic device (CPLD), a discrete gate or transistorlogic, discrete hardware components or any combination thereof designedto perform the functions described herein. Processors can exploitnano-scale architectures such as, but not limited to, molecular andquantum-dot based transistors, switches and gates, in order to optimizespace usage or enhance performance of user equipment. A processor canalso be implemented as a combination of computing processing units.

What has been described above includes mere examples of variousembodiments. It is, of course, not possible to describe everyconceivable combination of components or methodologies for purposes ofdescribing these examples, but one of ordinary skill in the art canrecognize that many further combinations and permutations of the presentembodiments are possible. Accordingly, the embodiments disclosed and/orclaimed herein are intended to embrace all such alterations,modifications and variations that fall within the spirit and scope ofthe appended claims. Furthermore, to the extent that the term “includes”is used in either the detailed description or the claims, such term isintended to be inclusive in a manner similar to the term “comprising” as“comprising” is interpreted when employed as a transitional word in aclaim.

In addition, a flow diagram may include a “start” and/or “continue”indication. The “start” and “continue” indications reflect that thesteps presented can optionally be incorporated in or otherwise used inconjunction with other routines. In this context, “start” indicates thebeginning of the first step presented and may be preceded by otheractivities not specifically shown. Further, the “continue” indicationreflects that the steps presented may be performed multiple times and/ormay be succeeded by other activities not specifically shown. Further,while a flow diagram indicates a particular ordering of steps, otherorderings are likewise possible provided that the principles ofcausality are maintained.

As may also be used herein, the term(s) “operably coupled to”, “coupledto”, and/or “coupling” includes direct coupling between items and/orindirect coupling between items via one or more intervening items. Suchitems and intervening items include, but are not limited to, junctions,communication paths, components, circuit elements, circuits, functionalblocks, and/or devices. As an example of indirect coupling, a signalconveyed from a first item to a second item may be modified by one ormore intervening items by modifying the form, nature or format ofinformation in a signal, while one or more elements of the informationin the signal are nevertheless conveyed in a manner than can berecognized by the second item. In a further example of indirectcoupling, an action in a first item can cause a reaction on the seconditem, as a result of actions and/or reactions in one or more interveningitems.

Although specific embodiments have been illustrated and describedherein, it should be appreciated that any arrangement which achieves thesame or similar purpose may be substituted for the embodiments describedor shown by the subject disclosure. The subject disclosure is intendedto cover any and all adaptations or variations of various embodiments.Combinations of the above embodiments, and other embodiments notspecifically described herein, can be used in the subject disclosure.For instance, one or more features from one or more embodiments can becombined with one or more features of one or more other embodiments. Inone or more embodiments, features that are positively recited can alsobe negatively recited and excluded from the embodiment with or withoutreplacement by another structural and/or functional feature. The stepsor functions described with respect to the embodiments of the subjectdisclosure can be performed in any order. The steps or functionsdescribed with respect to the embodiments of the subject disclosure canbe performed alone or in combination with other steps or functions ofthe subject disclosure, as well as from other embodiments or from othersteps that have not been described in the subject disclosure. Further,more than or less than all of the features described with respect to anembodiment can also be utilized.

The foregoing embodiments can be combined in whole or in part with theembodiments described in any of U.S. Patent Publication No. 2022/0069855(published on Mar. 3, 2022) and co-pending U.S. patent application Ser.No. 17/709,724 (filed on Mar. 31, 2022). For instance, embodiments ofone or more of the aforementioned U.S. publication and application canbe combined in whole or in part with embodiments of the subjectdisclosure. For example, one or more features and/or embodimentsdescribed in one or more of the aforementioned U.S. publication andapplication can be used in conjunction with (or as a substitute for) oneor more features and/or embodiments described herein, and vice versa.Accordingly, all sections of the aforementioned U.S. publication andapplication are incorporated herein by reference in their entirety.

What is claimed is:
 1. A polarization rotation system, comprising: aradio frequency (RF) mechanical device; and a plurality of reciprocalports for the RF mechanical device, the plurality of reciprocal portsincluding a first pair of reciprocal ports as inputs for the RFmechanical device, and a second pair of reciprocal ports as outputs forthe RF mechanical device, the RF mechanical device being configured toperform polarization rotation of signals to enable avoidance ofinterference.
 2. The polarization rotation system of claim 1, whereinthe polarization rotation is performed in an RF domain, wherein theinterference comprises passive intermodulation (PIM), and wherein thesignals comprise input signals and output signals of the RF mechanicaldevice.
 3. The polarization rotation system of claim 1, wherein thefirst pair of reciprocal ports interfaces with crossed-dipole radiatingelements of an antenna system, and wherein the second pair of reciprocalports interfaces with a remote radio unit (RRU) or a remote radio head(RRH).
 4. The polarization rotation system of claim 1, wherein the RFmechanical device is configured to perform the polarization rotation fortransmit (Tx) signals, receive (Rx) signals, or both, and wherein thepolarization rotation mimics physical rotation of crossed-dipoleradiating elements of an antenna system.
 5. The polarization rotationsystem of claim 1, further comprising: an additional RF mechanicaldevice; and a set of reciprocal ports for the additional RF mechanicaldevice, the set of reciprocal ports including reciprocal ports as inputsfor the additional RF mechanical device, and reciprocal ports as outputsfor the additional RF mechanical device, the additional RF mechanicaldevice being configured to perform polarization rotation of signals toenable avoidance of interference.
 6. The polarization rotation system ofclaim 1, wherein the polarization rotation system is implemented in anantenna system, in a radio, or in a standalone system that interfacesthe antenna system and the radio.
 7. A method, comprising: receiving, bya radio frequency (RF) mechanical device, signals relating to one ormore crossed-dipole radiating elements of an antenna system; performing,by the RF mechanical device, polarization rotation of the signals toderive output signals having polarizations that are rotated in a mannerthat mimics physical rotation of the one or more crossed-dipoleradiating elements; and providing, by the RF mechanical device, theoutput signals to enable avoidance of interference.
 8. The method ofclaim 7, wherein the polarization rotation is performed in an RF domain,and wherein the interference comprises passive intermodulation (PIM). 9.The method of claim 7, wherein the providing comprises providing theoutput signals to a remote radio unit (RRU) or a remote radio head(RRH).
 10. The method of claim 7, wherein the RF mechanical device isconfigured to perform the polarization rotation for transmit (Tx)signals, receive (Rx) signals, or both.
 11. The method of claim 7,wherein the RF mechanical device is implemented in the antenna system,in a radio, or in a standalone system that interfaces the antenna systemand the radio.
 12. The method of claim 7, wherein each crossed-dipoleradiating element of the one or more crossed-dipole radiating elementsoperates in multiple frequency bands.
 13. The method of claim 7, whereinthe RF mechanical device has a symmetrical configuration.
 14. Acommunications system, comprising: an antenna having multiple arrays oforthogonally-polarized radiating elements; and a device arranged tocommunicatively couple with one or more arrays of the multiple arrays oforthogonally-polarized radiating elements, the device being configuredto perform polarization rotation of signals relating to the one or morearrays, the polarization rotation mimicking physical rotation of the oneor more arrays and enabling mitigation of interference.
 15. Thecommunications system of claim 14, wherein the polarization rotation isperformed in a radio frequency (RF) domain, and wherein the interferencecomprises passive intermodulation (PIM).
 16. The communications systemof claim 14, wherein the device is configured to perform thepolarization rotation for transmit (Tx) signals, receive (Rx) signals,or both, and wherein the signals comprise input signals and outputsignals of the device.
 17. The communications system of claim 14,wherein the polarization rotation is integrated in the antenna.
 18. Thecommunications system of claim 14, wherein the polarization rotation isintegrated in a remote radio unit (RRU) or a remote radio head (RRH).19. The communications system of claim 14, wherein the polarizationrotation is at least partially performed using a motor, a driveassembly, or a combination thereof.
 20. The communications system ofclaim 14, wherein the device comprises one or more waveguides, one ormore cavities, or combinations thereof.